After Ireneus created the 8 Faiths, he created the mortal beings of Uthrandir. He started with humans, a greatly diverse species in their appearance and character. As humans developed their strong sense of adventure, curiosity led them to explore and settle across much of Uthrandir. In time, Ireneus grew bored of humanity’s great diversity and set out to create more distinct races. Whereas humans, in their great diversity rarely formed political unity and often fought amongst themselves, these newer races tended to be much more cohesive.
For player races, see here