What's worse is when you try to explain why a certain racial or ethnic group don't like to be called something around here they say "Well they need to stop being so sensitive."
Oh, I've seen this countless times. In reference to every single minority group. It always plays out as a gross combination of willing ignorance, social Darwinism, and an determined, utter refusal to acknowledge bad shit the US has done. The last one is set to get even worse in the future, as some states (like Oklahoma -- again) are passing laws that forbid the teaching of anything "unpatriotic" -- AKA: anything that makes the government look bad. I think they replaced their AP history material with -- no shit -- the 10 Commandments and Reagan speeches.
I can't count how many times I've seen a white person dismiss a terrible atrocity, or at least overlook the worst parts of it. "Slavery wasn't really all that awful. It was just common at the time, so America wasn't doing anything overly bad. And HEY, African societies had slaves too! So there! Stop whining!" Or "I don't feel any remorse for the civilians who died in Hiroshima, because the nukes ended the war early."
And then in regards to Natives, no matter what kind of discussion happens, you usually see this: "They lost, we won. They need to get over it and stop being so sensitive." Or, "Caesar didn't say 'I came, I saw, I felt really bad about conquering people.' This is the way society works. The strong dominate and conquer the weak."
Because that's a well adjusted thought.
Slavery is sometimes "justified" with those arguments, too. They aren't old arguments from a bygone age. The Caesar comment was something I saw recently on this video of Sacheen Littlefeather refusing to accept Marlon Brando's Oscar for the Godfather (note the loud booing -- it's also worth digging more into her story, because she was treated extremely shitty backstage. The reason she didn't read Brando's speech was because they threatened to arrest her if she did).
Unless you take AP history or get private tutoring, public schools teach a very "bleached/sanitized" version of history. Where I am, they just skipped over some of the more troubling stuff. I remember learning about the Revolution, Civil War, and the World Wars. Things like Vietnam and our mostly doomed "operations" in the modern era were glossed over. Slavery and the Native American genocide (which is indeed considered a flat-out genocide by other countries, but conveniently not in the US) were presented rather dryly, skipping the most gruesome details.
I learned most of my history in private study, just because I legitimately enjoy reading about it.
But when you consider that most Americans don't study history again after graduation, y'know... people learned that America was the best thing ever, and they don't like hearing otherwise once they've been molded. History classes in any country are often propaganda tools. Even documentaries on the Hitler-- I mean History -- channel only like to cover our "glorious" aspects.
All big expansionist nations have bloodstained history. Persia, China, Rome, Britain, the US -- the list goes on and on. You have to take the bad with the good, so you can learn from it. Part of becoming a more enlightened society means realizing how awful past barbarities were. Like how you look back on your childhood behavior and facepalm when you realize what a shit you sometimes were. None of that underscores the good things that happened along the way.
And if you really never actually have to encounter the race you supposedly don't like? Well, you'll never learn otherwise. That's why whitebred rural towns are cesspits for racism. Because it's a combination of this kind of teaching, plus learned racism, plus cultural isolation.