I'd categorize them as I would Witches from my world, really. Human-like in some respects, but of a different nature that doesn't quite understand us in our entirety, nor can we theirs, and each one settled into a well-worn and highly specific point of view by virtue of their semi-eternal existence.

Witches are created by human suffering, though. The Arcana simply Are, and they're unique in that respect, as far as I'm aware.