It even says in the book that they are advanced Facedancers. It’s clear that they were an extension of the idea of a FD not having a “core” or base personality, and would take on their copied personas. That in the scattering, they had absorbed so many memories that some new “self” had emerged. They maybe even had copied someone with prescience and even with deep other memory, seeing as they were expressing ancient earth customs.

IMO they were meant to be the ultimate Abomination, where another soul (other memory) didn’t take over someone’s body because there was no one “home” in the first place.

I think there was going to be a significant time jump as well.