The race of a person is determined by the material from which they were created. It isn't elves, dwarves, and humans; it is "of blood", "of tears", "of dirt", etc. Here they are, each pulled from an ancient near eastern text.

Race As Composition

D6	Material	Racial Bonus
1	Blood	A drop of your blood can purify contaminated or poisoned liquid.
2	Clay	If you soak a portion (or all) of your body, you can squeeze the soaked portion through spaces you otherwise would be unable to, up to half the width of the portion.
3	Corpse	You can "play dead" and enter a stasis for up to 24 hours, ceasing all bodily functions without consequence. You must rest and eat a meal to be able to enter stasis again.
4	Dirt	You can sense tremors within earth like one can see ripples in water.
5	Dust	If you are not seen, you may choose not to be heard as well.
6	Tears	You are a very believable actor.

Blood - Enuma Elish

Clay - Pyramid Texts, Enki and Nimmah

Corpse - Atrahasis

Dirt - Song of the Hoe, Hymn to E-engura

Dust - Genesis 1-2

Tears - Coffin Texts