Reathos wants more agressive sentient species, sees the human souls in the wraithstone, accesses memory (the Shadow part of a soul) and sees Logos and Elysium on Arcon. Proceeds to make a specie in mirror image of Logos' humans thinking that they will serve as sentient apex hunters.
That's my plan to make humans on Galbar...
That's as good a plan as any, I suppose.