A time travel story needs to begin with a premise, and some premises are more common than others. For example, it has a common trope in time travel scifi circles to day that “Everyone kills Hitler on their first trip.”
Then again, in nearly all of the actual scifi stories where somebody goes back in time to kill Hitler, things end up going wrong in one way or another. That’s probably because time travel gone wrong makes for a more interesting story than the alternative — a straight ahead win for the good guys.
To me what is most interesting about this particular trope is the “pre-crime” aspect of it. Young Adolf has not actually caused the death of millions of people, or even risen to power. Arguably his greatest crime is making bad art.
So he were actually to be killed, to prevent a future that would therefore never happen, would that actually be justifiable? Can you really justify a capital crime in the name of something that doesn’t happen?