It never did anything for the story. It might as well just not be there.
Besides it being said in the beginning, was anything else said about her previous/past life? It wasn't, right? (￣∇￣")
It is not even that she is mature for her age or her experience from the previous life influences her thinking or adapting. It is just there, probably because "reincarnation" and "isekai" are a thing now.
Chehov said:" if in the beginning of a play there is a gun on the wall, it must shoot by the end of the play".
This story has a whole arcenal of weapons that will probably never shoot.
I honestly forgot that Estelle was a reincarnation until I reread the summary and the first few chapters. (￣∇￣")