it's not that bad here
That's the opinion of our leading experts on the subject!
So, this walking incarnation of a specific kind of evil had a totally hypnotic charisma - as in, people would totally oppose him, and then listen to a recording of his speech and nod along. Now, we would consider that a positive quality on Earth, but he used that charisma to channel the overall resentment of people into willingness to commit unspeakable evils - starting from beating down political opponents for their mere opinions and later proceeding to killing peoples randomly blamed for everything at industrial scale, conducting heritage optimization, and preparing for bloody world conquest.
At first, nobody took him seriously. Then, everyone was too scared, and started making concessions in hopes of appeasement.
Of course, there was no appeasing Hitler. He had a grand vision of creating a superior species of superhumans, and as a natural logical consequence of that, killing or enslaving everyone else.
And so the Second World War started. It was bloody, relentless, horrific. Britain withstood a rain of missiles and bombs. Soviet Union drowned in blood. China got defiled by Japan. Africa got used as a battleground for outsiders. America leveled two cities with nukes and one with incendiary carpet bombing.
Now we are wiser, of course! We have learned well that all humans are exactly equal both morally and instrumentally, except for when they aren't.
For enveloping the whole world in a tide of violence and death, for an ideology of racial hatred and power for the sake of power, and for trying to improve upon humans who, as humans, are perfect as they are, Hitler is consigned to the indisputable position of the most evil and hated man in history.
I am feeling intensely uncomfortable.
Hey, Eris. Do I want to know what nukes are?
Nope.
"I just recently arrived here from an another world," says the boy who isn't a religious figure of any kind.
Notably not "the Persian Kingdom", although who know which name is associated with what, in this world.
A beacon of relatively advanced civilization amid total anarchy, here. Reza Pahlavi, the forward-thinking first Shah of the dynasty, ensured that his descendants would be Miracles, in a period where the first system shocks were only beginning to rock the planet.