> you can't just assume that existence is bounded by your living memories

I was going to raise that, but couldn't find a short enough way to describe it properly. Something like:

Existence beyond what you can actually remember doesn't matter because it's outside any bounds of practical discussion; it should be excluded from consideration. The same way it's impossible to predict anything 'before the big bang' because we only have 'after the big bang' as useful evidence. There is no way to verify any continuity if you can't remember it or if there is no evidence of it. There's no guarantee you can even comprehend what it could be, 'you' as a concept may not even exist and it's unlikely to be relate-able to anything in this living world. Maybe you return to being 0.00001% of the collective consciousness of the universe, or any other crackpot thing anyone wants to suggest. Flying Spaghetti Monster.".