Since no one can remember their past lives, I would say that it wouldn't much matter what we are next, or what we were before. All those things, what if you were those before? You could have been someone horrifically tortured to death in the Middle Ages/Dark Ages, but you wouldn't remember it now. So, it wouldn't much matter what you are in the next life.

Since there's no tracking from life to life, there's no purpose to it. Nothing is gained. Like if you were mean to a specific kind of person in one life, and you became one of those people (say, a Muslim, or an overweight person) in your next life. I mean so what? It's not like you learn your lesson, having gone from a bigot of privilege to the victim of said biogtry. Everyone has it rough somewhere. And no one gets out alive.

I used to know a guy in middle school who at one point, believed that there was a kind of active memory reincarnation. You don't remember while alive, but between lives you remember it all, so you choose or you are assigned a future life depending on what you need to learn to reach enlightenment. In that future life, your memory is wiped, but when you're done living that life, you have all the previous life memories and you keep doing that until you figure out what you need to in order to reach enlightenment. I don't think it was Buddhism or Taoism or any of those Eastern religions. It sounded made up. I don't recall the name. And he never really got involved with it, he was just telling me about it and I never quite forgot.