I don't think Rey is an ancient baby or anything of the sort. I'm sure she is 19 years old and was not preserved from a time long past. She's also not twins with Kylo or anyone else. He is confirmed to be 30 years old.
There are enough ancient figures in Star Wars, from Yoda to Maz to Snoke. Rey is a character for the current generation, she is young on purpose, not a blast from the past.
There are enough ancient figures in Star Wars, from Yoda to Maz to Snoke. Rey is a character for the current generation, she is young on purpose, not a blast from the past.