The term Ethnic Cleansing was not invented until the 1990's, to describe what was happening in the Balkans. The Serbs thought they were being enlightened and benevolent because they chose to forcibly relocate the Bosnian and Croatian populations... as opposed to the prior attempts at genocide, enslavement, and/or forced religeous conversion which had been the standard operating procedure for the prior 600 years in that land. The Serbian leadership was quite shocked when world opinion was united against them. They mistakenly thought that as long as they did not resort to Nazi-like levels of atrocity, they would get a pass. They thought that the use of large-scale rape as an instrument of terror, combined with selective small scale mass killings (hundreds at a time) would be ignored by the rest of the world. If the year had been 1890 instead of 1990, they would have been right.
So what is my point? When we look at the treatment of the Native Americans by the English, then by the American settlers, and later by the US Government, we need to keep this in context of what was going on in the rest of the world.
Slavery in the US did not end until 1865, and as bad as the Native Americans were treated, it was no worse than slavery, and often much better. Slavery continued in Brazil until 1888. Slavery was abolished in Saudi Arabia in 1962, and there were ~ 300,000 slaves in Saudi Arabia at that time.
During the Napoleonic wars in central Europe (1795 - 1813), civilians were used as canon fodder and human shields. The British were brutal in suppressing the Boers (1900 - 1915). The Turks tried to genocide the Armenians (~1900). All manner of slavery and sexual bondage existed in China, Japan, India, Arabia and Persia and was both legal socially acceptable(up to ~1940).
The Aztecs brought human sacrifice to a whole new level. To consecrate their new pyramid temple, they basically painted the entire pyramid with human blood. By their own account, 84,000 captives were slaughtered in a matter of days. Even allowing for exageration, it was probably at least 10,000 people.
So let's keep things in perspective. The Native Americans were brutalized by the US government, and the American people just didn't care about it. Hard truth, but truth nonetheless. But the brutalization was not exceptional, or unprecedented. In fact it was an average, or even mild-level of brutalization compared to what was going on all over the world.