Yeah, Bibi lived a pretty shitty life (not a reincarnator but a regressor aka same identity and body etc) lived terribly then died terribly. Managed to regress to when she was a child and with memories of her past life she got herself adopted and so on (think of her as one of those child regressor story protagonists except that since she lived terribly she's not a genius or someone who plots and thinks of every outcome like the usual protagonists, just someone who's hardworking and still a bit naive so she still kinda maintains that child like innocence)
Cause at first everything she remembered at first was based off a book where the protagonist is bibi. In that book bibi had a bad first life and now has a great second life. In that second life she plays the villainess to bibi (all based on the book)
In this life however she was one, able to keep all of the book information and then realizing that it’s also her second time living this life in that world

huh wait did i skip a chapter or something? i don't understand why titania says bibi is a regressor, and she had a bad previous life. so does bibi have memories of her past life as well? and she chose to change it? i'm so confused