No-one knows how humans originated. The elder races first noticed them millennia ago, and have watched them develop into the dominant people of the world. Some say a powerful void entity created them as slaves.
Humans are unusual in that they have no spirit, but have the capacity for it. This makes them shades in the mists, all the ghostly shades of men wafting hither and thither amidst the timeless ether. Some say even the souls of men disperse in the end, and it is this soul-stuff which forms the mists themselves.
The High Men who fought on the side of the gods against the great void demon are imbued with spirit. Human PCs can be High Men but must purchase Spiritual stats from their standard pool of character points. To be a pure blooded High Man all a characters Spiritual stats must be at least one. Characters with zero in any Spiritual stat are of mixed blood.