Chinese people built many of America's nineteenth century railroads, didn't they?
Then you got Chinese laundries, and so on. Very large numbers of workers.
Americans back then were worried about racial mixing and cultural issues. So they opposed them becoming citizens. Barred them by statute.
Vague memories on my part.
But you ended up with a policy of not worrying about such things, which is another part of the American story. Many Americans like that and feel proud that you figured it out. You wouldn't have needed to if it was obvious.
The lesson of American history, in my view, is that it is a mistake to depend upon a virtuous, heroic narrative. People are imperfect. American history is littered with issues, just like every other country's history is. As you say, the point is to learn, change, try to deal with the problems our own generation experiences. It's a good idea to be modest, because everyone is going to point out the flaws in a boastful nation.
But blaming people for the way they behaved in the past (which you haven't done but many do) is not a useful way to do history. And demanding reparations for events that happened long ago is crackers. Everyone has had a rough ride at some point. That's our common human story.