I’m not trying to promote extra lives or anything, but how are you sure about only one lifetime? Buddhists describe rebirth, like passing one flame on one wick to another wick. It would still be the same flame, different wick. I dont know that rebirth happens. Just like you dont know for certain about one life.
Thats okay, it would be very hard (but not impossible) for me to change my mind. I’ll take your word for it, and try to make today a good one, given how few are left.
The exact same neurons in the exact same proportion could possibly be reconstructed again and again. And then that animal thing could experience “you” again. And since you are a product of the invironment . The same “You” can only exist from the exact same parents, schooling, television, national and international events, religion, etc… It’s possible. But “you” will never exist ever at any other place or time.