Um.... Basically no matter how much explainable reason you want to put it, my basic guess to compare your basic question is that some lazy god has so many reincarnators lined up and has to deal with all of them but doesn't want to populate the world with some rando and decides to make a body which would be inhabited by a protag and everytime the person dies, he reuses it by reverting it back to new and put a new soul into that sht and shoved it to some random woman and say 'Congrat's btch, you now carry a gifted child'. And it became an automatic routine of dying and reverting it back to new and shoved it to some random woman and thats it.
It gives perspective as to why there's no parents since you don't have one and your mother gets killed after you are born and get adopted to a new family.
