it was americans. even if the government helped, it was common americans, poor and rich, who murdered and repressed natives every day until the land was solidly occupied.

Even so, there have been Americans who opposed what their country and countrypeople were doing, and fought to oppose it. Were they in the minority? At times, sure, but the American political system has always given disproportionate power, first to landowning Anglo-Saxon Christian men and now to (still predominantly the same group tbh) rich people and the people they get to follow them.

the average american was evil back then and remains evil as fuck to this day, because that's what not being an anti-imperialist leftist tends to mean if you live right in the middle of the imperial core

If you view everyone who isn't actively radicalized as evil then I think you're losing touch with some of the very people that need to also be radicalised. The "average American", when polled time and time again routinely profess to have viewpoints waaaaaay to the left of mainstream discourse. Is it not our job as socialists to get to the see the full extent of what it means to really believe in equality and justice?