From what I've read re: the early American frontier, you are painting with a very very wide brush here, my friend. You've managed to lump over 100 distinct tribes with distinct cultures into the pejorative term "Indians".
To be sure, some of these cultures were strange and "barbaric" (by your standards; certainly not theirs) and tho culturally different from you...and certainly from the early French and Spanish europeans, they were absolutely normal for their time and place and acting as they should.
No, my friend, not "barbaric" - not by their own standards, and not by neighboring tribe's standards. "Warlike", "Agressive", "Dominant" to be sure, but "barbaric"??? I think not.
Your definition of "barbaric" comes from your cultural mores and standards that you are busily trying to "overlay" on top of their culture, then castigating them because they do not measure up to your expectations.
Leave them to their culture. If I may paraphrase, "it is what it was", and let's leave it at that.
Yes my friend, they were barbaric, if they weren’t, then no people have been so.
This is what it always comes down to with the brainwashed, they can only defend their error with their thoroughly propagandized brain. They use terms like "pejorative", or "offensive" to obfiscate the truth. The term "Indian" was never intended by those who first used it to be a 'pejorative', hence it cannot be one now unless someone tries to distort history for their own purposes. Terming the aboriginies of America "Indians" was a simple mistake in sea navigation, believing they had arrived in India. If anything, it is a pejorative for Columbus and the early explorers, because it highlites their navigational mistake.
As for painting the 100 Indian tribes with a "broad brush", that's just another page from the liberal book of "nothing is black and white, there is mostly just gray area". That's why I couldn't read the rest of your post. You've been thoroughly brainwashed and there's nothing I can say that will change you.