Mutations.
Evolutionary paths determined the internal structure of a beast, and if it was humanoid, it would have a Class like humans, Sif and Giants, but if it was not, it would have a mutation instead.
A mutation was a sort of a unique bodily trait outside the bounds of abilities exclusively granted by virtue of being part of a particular species. Unconventional mix breeding, consuming other outlandish beasts, and coming into contact with mystical geographical phenomena were a few of the ways mutations could be born.
Thus, like Classes, there was an unlimited assortment of mutations.
That said...
'Is the set of abilities from this creature something from a mutation? It hasn't shown anything unique besides being fast and having sharp claws,' Skullius wondered.
In the next moment, his enemy which was bathed in restless, radiant bolts of lightning streaking from its now white furs that stood aloof, as if livid with rage of their own, pounced.
