We killed them and displaced the rest so damn fast that we forgot all the major slurs for them

"Savages", "Redskins”, "Squaw", and so on.

Some news headlines even refer to the second one as "the R-word":

CNN: The terrible R-word that football needed to lose

Politico: The R-Word Is Even Worse Than You Think

These are extremely harmful words with hundreds of years of genocide behind them. I imagine the only reason they aren't censored like the N-word is is because Native Americans make up a proportionally smaller population due to the effectiveness of the genocide, and because the reservation system is in contrast to racial integration as with American black people in so much as it limits interactions between them and racist whites who would overuse a dehumanizing phrase to the same extent.