Life in the Forgotten Realms in general very much resembles that of life on earth during the middle ages period, with a few differences caused by the existence of magic and the divine.
The vast majority of people in the Forgotten Realms are classified as commoners, they are the peasant folk of the land born to neither wealth nor titles, and can look forward to a short life of toil and hardship until the perish from illness or misadventure.
Commoners are those people who suffer a subsistence based existence. Whatever work they perform; be it blacksmith, miller, baker, farmer, indentured serf, their toils serve only to acquire just enough wealth to allow them to purchase buy food, shelter and keep their livelihood in operation.
A commoner will typical earn the equivalent of a few copper pieces per day (1-10) with costs of up to 70%. This severely limits the purchasing power of the common folk, all food items are likely to be of low quality as is clothing and shelter, an item such as a sword or other piece of combat ready equipment would require a lifetime of saving and as such becomes a valuable heirloom that is passed down for many generations.
Commoners in rural and urban settings differ only in the jobs they perform. In the countryside a commoner could be a farmer or a forested or a hunter, but in a town or city a commoner could be a dockhand, a cleaner, a shop assistant or other menial tasks that are not desirable jobs.
The middle class is a concept that generally only exists in an urban setting where there is greater purchasing power than normal, created by the concentration of people and nobility .
The middle class are those people that can command higher than subsistence rates for their work. Thus means the middle class generally provide something for the nobility or other middle class and so hold jobs such as craftsmen or merchant.
A member of the middle class generally the equivalent of a silver piece every day (50-200 copper pieces), with costs of up to 60%. The middle class are able to afford better food, clothing, and housing with enough left over to purchase luxury items.
There are some middle class who earn as much as lesser nobility and in the more mercantile or cosmopolitan cities, these middle class are supplanting the traditional nobility.
As the middle class require a minimum purchasing power of the local population to exist it is rare for people of this status to exist in the countryside unless theirs services have a local noble patron (such as a village blacksmith who makes weapons for a nearby lord), or they have business elsewhere that support the lack of business.
It is possible for middle class to hold similar jobs to the commonfolk, in which case the only distinction between the status of individuals is the amount of income these people generate.
The noble classes are special in that their status is not necessarily derived from their wealth and disposable income but instead from titles that they hold as bestowed by their birth or by royalty (or a council of their peers).
The nobility typically earn the equivalent of one or more gold pieces per day (50 to 200 silver pieces), with costs that range from 80 to 100+%. The nobility have an expected standard of living that means they are often forced to spend almost all of their disposable income on accommodation, food and clothing. In some cases (those courting the influence of rulers for example), the costs can be many times a noble’s income, with the noble in question gambling on receiving royal favours at a later date.
Nobles in the countryside and urban settings have little distinction from their urban counterparts, with the full range of lesser and greater nobility being found throughout. Those nobles who court the favour of a ruler at the capital generally tend to have the greater incomes but also live incredibly extravagant lifestyles.
It is a widely accepted “fact” in the Forgotten Realms that the gods are real and can affect the daily lives of people for good or ill.
The deities are served by many temples and churches which all preach a similar message; “pay homage to my god and reap the rewards, ignore my god and suffer the consequences”. The degree to which people believe and adhere to these words vary depending upon a person’s education and status.
The common folk in general have limited education and limited wealth to sacrifice to the gods. There are so many different gods in each region that even if a person were to sacrifice 1% of his monthly income to each God he would quickly be destitute.
The commonfolk accept that there are many different gods and religions and they understand very little about any of them, they will sacrifice as little as they can on an annual basis to each deity that directly benefits their existence. These sacrifices rarely include money if it can be helped, and are often made during days of special significance to that particular faith (or whenever the commoner has free time). If there is a local shrine the offering will be made there, otherwise it will occur wherever the person believes would be significant to the deity (such as burying it in the ground or throwing it in the water) or if a travelling preacher happens to pass by then such an offering will be made in their presence.
Commoners do not devote themselves to a single deity unless such a behaviour was inherited from their parents or if there is a large temple nearby. In the case of such devotion to a single deity, those commoners merely make such to sacrifice more and more often to that single God and perhaps attend a sermon or two if possible.
The commonfolk make little distinction between the various supernormal manifestations around them. God’s, monsters, wizards, magic, storms, floods, etc, to a commoners mind they are all connected and all mysterious. As a result any sudden strange occurance can result in a surge in donations to the gods and many unscrupulous priests will exploit this superstitious behaviour.
The middle class generally have better education than the common folk. As a result their understanding of the divine is much better (or so they believe) and the rate of devotion among these people is much higher as most available texts are religious in nature and created by the various religions.
Middle Class folk still pay homage to a variety of different gods, sacrifing a small percentage of monetary wealth to those gods that benefit (or might hinder) them. These offerings are generally made at local temples (which are more numerous in urban settings), and are accompanied by attendance at sermons on a monthly basis (to those most favoured).
A member of the middle classes is more likely to show special devotion to a single deity, and this devotion is usually based on personal preference than anything else. The favoured deity receives weekly attendance at sermons and every holy day as well as much greater offerings.
The middle class understand that not all monsters are sent by the gods, nor are wizards the same as priests. These people are likely to at least attempt an understanding of the church dogma and follow it as best they can (without disrupting their lives). Still, their are those in the middle classes who behave as commoners do and pay lip service to the gods and little else.
Most priests come from a middle class background.
The nobility are again apart from the other classes. Their free time and wealth means that they are more able to devote themselves to the gods (as priests would like), but those same privileges as well as a higher status mean very few wish to serve anyone else (and that includes a god).
Nobles will typically only show patronage to a handful of churches, based on current circumstances, family bias, and personal preference. This patronage is a sign of status, often very public and designed to curry favour with noble and commoner alike.
If a noble shows devotion to a single deity it will almost always be a family tradition. Such devotion can often be perverse and fanatical in nature, as the nobles often have personal shrines and attending priests and so are more prone to the extremes of personal ideology. While a noble is unlikely to become a priest in a church they are very likely to found or join a cult or cabal for their own gain.
Successful adventurers (I.e. those that don’t die during their first foray) are truly exceptional individuals. It is a rare thing for a person of any status (noble, commoner, etc) to hold more than one level in any character class.
Your average commoner is likely to know one or two skills (farming, smithing, hunting, etc), and he will utilise those skills every day of his life, many times a day. With the experience from such an existence over a 20 year period (the average working lifespan) it is nearly impossible for such a individual to advance a level.
Middle Class and nobility are likewise afflicted. Despite their greater breadth of knowledge and understanding of language, combat, diplomacy, craft, etc, it is unlikely such an individual will gain an additional level of experience. Those nobles and middle class surviving into old age may have a chance of advancement but the penalties of old age counteract any benefits they may receive.
The distinction between others and adventurers which allows the acquisition of incredible feats of skill and endurance are down to their inherent capabilities and their willingness to test and exceed their limits on a regular (almost daily basis).
As a result the average npc is little more than a single level minion, capable of performing a single task to moderate success but unlikely to compete with an adventurer on any level (although for adventurers that typically involves violence and death).
Even those individuals that profess to be warriors, wizards, priests, and thieves, are little more than a single level minion whose chosen greatest skill is the ability to swing a sword or pick a pocket.
Not all soldiers, militiamen, thugs, and mercenaries are accomplished warriors on a par with an adventurer. 90% of these individuals are single level minion who can hold a sword with chopping off their own limbs. The remaining 10% may truly hold a level in the warrior class at a single level (or maybe 2). If an individual was exceptional enough to be on a par with an adventurers skill in battle he wouldn’t hold down such a menial job.
Not all wizards even hold a level in the magic user class. There are many natural phenomenon (substances that smoke on contact with air or water, ores that explode on impact,) that would allow an individual to masquerade as a wizard to a village without anyone suspecting the truth.
Similarly not every priest can cast a spell (or even read magic), there are many talents desired by churches some of which are more important than magic use (such as charisma and power to persuade and convert people to your faith). Those individuals who can cast spells may be able to do little more than make light appear in their hand but is sufficient enough to wow the uneducated.
Character Classes are for the truly special and those with more than one level are rare individuals indeed. Typically only those truly rare individuals receive a name and some detail, but do not assume they are the norm or represent even a tiny fraction of the population.