Didn't the indigenous people not believe in "land ownership"? If so, that means it was never "stolen". But I still see your point. No human is illegal on Earth.
You guys need to seriously stop hyper focusing on trying to undo shit that's already happened that can't be undone instead of trying to.... prevent further colonization from happening? Isn't progressivism about changing the future? Not the past?
I'm not condoning colonialism, but without it, there would still be indigenous American peoples stuck in the past. Plus, I (and many others) wouldn't exist.