FWIW, I can state with a high degree of certainty that killing Hitler would probably, and a bit ironically, snuff me out of existence. My paternal grandparents emigrated from Austria fleeing the Nazis, so no Nazis means in all likelihood my parents never meet.
Of course, if Hitler's victorious then my life probably takes a turn for the worse as well.
History is an interesting thing--mess with it, and you could be playing with things you don't know. Twilight Zone has dealt with stuff like this, and may do so again now that it's back.
In the Star Trek franchise 'god' has no right to play god. Did you watch the TOS episode about Apollo and the STV movie?
Kirk fought a greek god and won. But that's an entirely different topic. It was established that Apollo was no god--but an alien that would appear godlike because he could do stuff. Apollo wasn't behaving like a god. He was behaving like an enslaver.
I believe killing Hitler would result in someone else leading the party since the reasons behind WW2 still existed. In order to prevent WW2 you would need to stop the assassination of Archduke Ferdinand and prevent WW1. Go back even further and stop European imperialism.
We will never know. WWII was almost a second act to WWI, because the Germans were so viciously punished after it. But perhaps a better leader than Hitler could have led Germany to a resurgence in a more peaceful manner. While post-WWII Japan was the beneficiary of the lessons learned from WWI, Japan after surrender became a much better country and an important part of the world today.
And if Hitler is killed when he's young, my family is three times larger. Instead, they were mowed down by Einsatzgruppen outside of Kiev. Of course, the NS had many awful, vile people who could take Hitler's place.
As would be the same with other people, who would have met other people, married other people, interacted with other people, and the odds of you being born are far lower.
Not to criticize you, but I think that the essential problem with time travel is that it is selfish, even with the best of intentions. It means picking a way that events move forward based on one's knowledge (which is likely limited) and interests. Unfortunately, it also means that those events won't be organically linked to those that came before. At least in previous episodes, there was a sense of correcting changes made to the past rather than engineering a past one wants.
It should also be noted that the further back you go, the worse it is. The past owes nothing to the future. But the future owes everything to the past. If you travel back in time 30 seconds, the only history you change is 30 seconds. If you travel back 30 years, you affect 30 years.
The only real exception is something the time traveler likely can't know, which is a predestination paradox. The real timeline actually unfolded because the time traveler was there, and if the time travel is prevented, THAT changes history. The only way to know though is after the adventure, nothing changed.
Saving Edith Keeler changed the world. Saving 2 humpback whales was always supposed to happen.
After all, who knows what happened with the man who vaporized himself in City? Do we know that Gillian's departure had no impact? Even if she was going to get hit by a bus the next day, would that not have impact on the person who hit her and ripple outward from there?
STIV is a perfect predestination paradox. Every issue you have is a proper concern, but we know for a fact that everything was what it should be because the second Kirk came back, everyone was in the exact same spot. Right to the conversation. Gillian was supposed to come to the 23rd century. As for the guy who got vaporized in City on the Edge, they got very lucky.
However, the motivation is far different than Janeway's. Janeway ruined a perfectly good timeline. Kirk saved Earth from imminent destruction, and given that he returned at the exact moment he left, he did not actually alter history.
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