In this scenario I would imagine Rey was an immaculate conception like Anakin, only she happened to be born to a couple of scavengers who didn’t realize it, and not knowing what to do with a child they just sold her off. It’s an interesting contrast to Shmi, who chose to lovingly raise Anakin. The vision Rey has in the cave in TLJ could also be seen as the Force telling Rey she has no real parents, she sees only herself.

I also think we could give Luke some dialogue about bringing balance later on Ahch-To, with Kylo instead focusing on the fact Rey has the same power as Vader had, this would stoke Rey’s fear of falling to the dark side, becoming the “new Vader” Snoke believed Kylo would become.