Humans are widespread all over Stone, particularly on Terras, where they have built vast kingdoms and empires. It is very rare to be in a crowded bazaar with no humans around. They are the dominant race, likely because of their ability to excel at anything. However, Humans can be as evil as they can be good, and are often the least ethical of the civilized races.
Humans will follow whatever religion they like, not content to be constrained by the traditions of their ancestors (unless that is their religion).
As previously expressed, Humans can have any sort of personality, and if there is any one common trait between humans it is their impatience and ambition.
As stated in the PHB (pg 29), humans vary as much as the world they live in. Usually the further north, the more fair, and the further south, the darker.