Aside from the obvious...

Humans are the most widespread and prevalent of races both in the medieval and futuristic periods. Humans are the race most likely to use technology, war amongst themselves, and belong to religious groups. Their cultures and appearance vary immensely. In the medieval time, humans are capable of magic working, by ritual, by sympathy with nature, or by religion.

In the futuristic period, humans are an advanced civilisation, with space travel and other technologies used widely. While they don't differ significantly from their medieval counterparts, humans have been able to mould and alter themselves by genetic manipulation, and by embracing a symbiosis with cybernetic technology. These categories are discussed seperately.