The butterfly effects would add up and and any zygote formed would not be the hitler-as-we-know anymore, since it would be a different combination of sperm and eggs.
Who needs guns when you got a time machine? Don’t like your highschool bully, just bump into their parents back in time. Or you know, “bump” ( ͡° ͜ʖ ͡°) into their parents.
I read a short story… I don’t remember the name of it… Anyway the guy goes back in time and kills Hitler, only to discover upon his return that everything was worse. So he went back and stopped himself.
Possibly “Making History” by Stephen Fry - although at 380 pages it doesn’t quite match as a short story, and the protagonist doesn’t stop himself so much as do something else to reverse the effects of his actions to save Hitler.