This isn't going to be some existential pondering or speculative thinking or any such thing. I'm going to stick with realism. And I'm going ask you to go to some very dark places (literally dark places). I'm going you to make you a star of a story. You can be yourself and you will be in a what if scenario. This scenario may help you figure out something about your past. I won't be making many statements but I will make you think.
You get captured by a group of people. They are taking you to some place and make you strip and get into something like a bag made of some soft rubber-like substance. They push you into the bag and close it shut. It's so tiny you have to crawl inside the bag. It's all dark and you are like a kid trapped in an odd sleeping bag. You get carried to some place and you feel like you got surrounded by hard sponge walls from all sides. You are trapped. You can barely move and it's all dark and you barely hear some random voices.
Then comes a liquid into the prison you are trapped in. You don't know what the liquid is. It just fills up the bag. Don't worry. This isn't the end of line for you. You have far more to go. The liquid starts filling up your lungs. You are in total darkness trapped in a tiny place suffocating on a liquid. But this isn't going to kill you. You find yourself functioning without any problem. This is called Liquid Breathing. This was featured in James Cameron's The Abyss (Including a real life filming) and one of My favorite anime ever; Neon Genesis Evangelion.
Then you suddenly figure out that these kidnappers of your's messed with your body and suddenly a tentacle gets connected to your body which is going to take control of your bloodstreams. You get all your nutrients through the tentacle thingy and all your bodily wastes are going to be taken care of by whatever the mechanism that the tentacle is connected to.
Now you are lonely. You are in darkness and you have an odd liquid all over you and completely inside you while being connected to some cable. How are you feeling? What do you have to say about life? Do you want to continue this? Do you want to live this life? How long do you think you can live without human connections? Do you think of humans as social creatures? Now here is some news: You are going to be like this for hours.... for days.... for weeks.... for months.
As a person.... as a human being.... how much of yourself would be left after the whole ordeal?
It's a simple question that can only be answered with deep introspection. So what will be your answer? Ask yourself how well you would have taken your origin story. This is your life. This is your past and don't ask why you don't remember any of this. Even PTSD never gets this bad. What if you had a past life? Do you think you'd remember? How did you even end up sane after going through a scenario like the horror story I put you in?