USW: Tip the World Over on Its Side
The archetypes are the primordial characters embodied by avatars. Think of them as the Platonic ideal of a character, like Jungian archetypes or the major arcana of the Tarot — they could be the representation of the Father, the Mother, the Soldier, whatever. Think of all the archetypes and symbols that appear in folklore, religion, and stories; any of them might be archetypes out there somewhere.
Who knows how many archetypes there are?