one of the most evil human beings to ever walk the earth.

one of the 10,000 most evil humans who will have ever lived

Ok, to me, these are two very different statements. "Most ever on earth" to me would be like top 3, top 5, top 10, something like that. Even 100 or 1,000 maaaaaybe, since we're talking about all of human history. I would agree Putin is maybe in the worst top 10,000 humans ever, but I guess I interpreted "one of most evil to ever exist" as a more rarified club. But the wording was ambiguous/imprecise so I'll give benefit of the doubt that's what you meant. And by that definition, yes, he probably fits.

Also, Dan Carlin is meh at best, never understood reddit love affair with him. He's a former radio host and political commenter who puts out some decent pop-ed/pop-history podcasts. If I knew a young kid in HS who had a burgeoning interest in history, and wanted to give them some easily-digested surface level takes on the subject I'd point them at some of his work, along with some of the other 'animated history' YouTube channels like Ancient History Guy, Armchair Historian, History Matters, Stefan Milo etc. But I strongly encourage you to expand to other more in-depth resources, those from history academics/researchers, etc. if you'vr got an interest. Dan is okay to discover a topic you never heard of, or to get the basics on a subject. Diving in to the deep end can be really satisfying and interesting, and I've found the greater depth of detail allows you to piece together and synthesize the data to construct your own understanding.