EXACTLY. That's why Arara's so suspicious about them. Humans and Grimm were both mentioned in the Creation Myth, so what the hell are Faunus? Just another evolution of an animal? Except why is there such a massive variety of them?

Essentially, she sees them as sub-human mutants, or some advanced ape. Maybe Faunus were originally the creation of humans, which was why humans thought themselves as superior the first place.