At the time of the breaking there was an incredible variety of human cultures each with it’s own racial stock, languages, dialects, traditions and religions. In the time since humanity has come under the power of the dragonborn, these old ways have been nearly erased. Slaves have interbred to produce broad variation in appearance. Skin color varies from light to dark with wide ranges in body types, hair and eye color. Language has been combined into what is termed slave speak by the dragonborn. For practical reasons all slaves speak draconic. Some of the younger generations no longer speak the slave tongue.
The dragonborn forbid any religion other than that devoted to their goddess, but it is likely that the slaves have kept many of their old ways secret from their captors. Somewhere in the slave population there may be cults devoted to old gods who have not shown their presence since the breaking. Perhaps they are dead, or never existed.
So far as the dragonborn and their human slaves know, there are no communities of free men living on this world.