Humans

Humans are the weakest of the important species, and also the most stupid. However, they make up the vast majority of the universe's intelligent population and frequently make up the lower class of many kingdoms. Originally confined to a single planet not that long ago, ever since the first contact between them and Space creatures, they have begun a massive diaspora and quintillions of humans have immigrated to interstellar kingdoms.

Overview
Humans are prone to starting wars and beating each other up, and die very frequently. They are often used as slaves or servants by Space creatures, although fortunately slavery has started to die out as Space creatures start to accept that humans really do count as intelligent species. Humans are fleshy meatbags who are easily killed, but have nonetheless adapted to their surroundings and developed a functioning society. Despite their tendency to kill each other for no good reason, their society was working very well until the Space creatures came along and enslaved them. Nowadays, humans are no longer enslaved but the majority of their population still works at low-level jobs for Space creatures, especially housekeeping jobs. There are, however, designated planets in each of the kingdoms where humans are allowed to build their own cities (mostly) free from Space creature interference.