> It was much more convenient to declare the native Americans as barbarians with little culture & society and the land unused and open to be claimed by European settlers.

I went to a US public school in the South and also went to a private school. We spent most semesters of history learning about Native American civilizations, construction, and at one point had to build small-scale physical replicas of their cities.

That's to say, I don't really buy your explanation for the broader US. Maybe specific pockets. What I do think is more likely is that people believe that warring kingdoms were still normal back then and view Native American tribes as just that - kingdoms that were conquered. That much I can live with, but the constant lying and taking back promises we made to the Native Americans is absolute trash and should be rectified.