Imagine that the hug changed the family, made them loving and supportive, and Hitler was just a recidivist incel who was destined to be hateful. Sometimes things can't be changed, some people don't want to be fixed, and some shitheads need to be rejected for who they are.
Honestly, you'd need to fix World War 1 and uhhh... Good luck. Hitler was just the drug addict the bitter world war 1 veterans and conservatives rallied around. There were multiple options. They all had similar stories, massive PTSD, using drugs and propaganda to cope.
Hitler's father was quite cosmopolitan. He had a nationalist history teacher and a rough time after he was rejected from art school. Take that with a huge grain of salt since this is how he depicts it in his autobiography. I think the major part of his radicalization was in prison while he wrote Mein Kampf but that's just my opinion.
Interwar Germany wasn't meant to work. It was a collective punishment over a war the entire nobility of Europe jumped into with all the fervor of a kid with a new wargame.
I kind of think about things like this a lot because of my family. My mom's parents were amazing. My mom was amazing. Her brother.. total asshole. My dad's parents - especially his mom - were beyond awful. Out of 6 kids, only 2 turned out good, and 1 was my dad. He's told me so many times over the years how he swore he'd never be like his parents. I've wondered before how things might have turned out of my maternal grandparents had been awful and my paternal ones good. I wonder how things would have changed.
With the social climate of the time, there would just be another guy who would replace him. It's a fallacy to think "fixing" the individual will solve social problems.
I've actually thought about this type of thing quite a lot, and I've come to the conclusion that you'd have to go back to the first Sumerian cities, and convince all the regular peaceful cooperative people to kick out anyone who says anything along the lines of "do what I say or I'll kill you".
It wasn't even "do what I say or I'll kill you". It was "this land is mine" - the establishment of private property. The lords never needed to explicitly make a death threat themselves when nature could make the death threat for them, and the victim is deprived of access to vital resources.
But being territorial with violence as enforcement goes back fast beyond that. Look at large cats or various primates. Yes the latter have enclaves but they are enclaves and tend to have a bruiser at the top
With that humans possibly gone extinct due to diseases introduced on that timeline. On the other hand the time travellers just bought a new disease to the current timeline.
May I suggest a plush monkey and not an actual live one? Real monkeys may react violently to an unexpected hug.
... which is kind of my way of saying that this comic would probably not go as shown, and the true ending might have been the cause of that particular family line seeing violence as an occasional necessity...