Just about everything.

You don’t have to like their domestic policies, but they’ve been more than reasonable in their relationship to the international community. That can’t be said about any government in Western Europe or their rabid dog occupying Palestine.

I don’t think that’s fair, that’s a child. Children can get infatuated with people and they don’t have the experience or the frame of reference to measure the consequences.

other people in the world absolutely were using the term American to refer to citizens of the US before the 1900s.

I mean, a few, I imagine. There’s always been people saying shit wrong. Would help your case if you actually had a source and not just a vibe to refute an evidence based position.

By population, however, most of the world isn’t the anglosphere. Spanish speakers, which is most of America, by and large call you “Estadunidenses” whenever it’s not “gringo”. A good chunk of us also speak English and object to gringos colonizing “america” much like Indonesians or Indians or Malaysians probably would have if Japan decided it was “Asia”.

You might not have decided that we speak English, but the same government that made it a necessity for us in the global south to learn the language is the one that decided to steal that term. Language matters.