It seemed mostly straightforward to me but maybe I didn't get it? It's a bunch of stories through time following the decay and collapse of human civilization that mostly have a "slavery and dehumanization is bad but there's hope because the human spirit" sort of theme, with the narratives connected mostly by the characters reading and being inspired by the records of the previous character's story. They all end partway on a misleading cliffhanger, and then in the second part of the book it works through them backwards to give the endings. Also maybe they are reincarnations of each other but it's ambiguous and doesn't affect the plot afaik.