[jessaustin]

I am not Native American, but perhaps I can answer your questions about USA culture in general. Lots of people know about the genocide in an intellectual sense, although that doesn't affect their politics and they don't appreciate reminders.

Free speech protections weren't obviously relevant to the genocide as it has occurred, although it wouldn't surprise me to learn e.g. that a native counterpart to Frederick Douglass had been silenced unfairly. As for speech in the other direction, the worst things were said (and done) by the "greatest statesmen" [0] so I doubt that corporate speech codes would have been much help. If it isn't too presumptuous of me to observe, it's unlikely that such things would have done much to slow down Hitler or Mussolini either.

[0] https://indiancountrytoday.com/archive/nice-day-for-a-genoci...