Honestly something that always pops in my head as well. Also why I find so many movies, tv shows with alternate dimensions etc... interpretation of time travel so ridiculous.

I mean theoretically the aspect of what makes you... well you, comes down to literally which one of millions of sperm happens to hit an egg etc... Bottom line is, your dad's schedule is adjusted by .3 seconds, he takes 1 step more on a street than he wouldn't have, he eats a different breakfast one month before, that's a whole reroll of the entire genetic dice. Someone being essentially the exact same person in 2000, in an alternate timeline where the nazi's won WW2, is such an absurd concept it's completely ridiculous. The idea of timelines or dimensions where, every person is roughly the same people they are, but the world itself is different, is pretty absurd to me. Marty McFly undid his existence the moment he slightly changed his mothers schedule, Making sure she got together with her dad, would not have been nearly enough to fix that.

Honestly I think the very concept of backwards time travel would by definition self correct.

Hypothetically Joe Smith invents the time machine, somewhere down the line, someone slightly alters the past, ripple effects, now Terry Jones invents the time machine instead of Joe Smith (which is it's own paradox, but assuming the effects of joes actions still are in place), Terry has a different concept, different people go in and use it, a different change is made, someone else invents the time machine. Ad infinium, the universal dice keep on re-rolling, no time line ever is final until, we get a timeline where the time machine isn't made, most likely due to extinction of the species that could have created it, prior to reaching the technological level that makes it. Or something completely destroys the resource needed to make it or similar.