The early United States was on the way to being an individualistic society, but hadn't arrived. In particular the natives who they killed they saw as part of a group, and not as individuals.
There is a long and complicated history in English speaking people of "rights for me, but not for thee" which started with the king, was broadened to nobles with the Magna Carta, was broadened to rich landowners with the establishment of Parliament, was in the process of being broadened to free white men around the time of the American Revolution and has piecemeal been given to other groups over time.
What today we consider "universal rights" were historically not universal. Our awful treatment of others is tied to our not granting rights to them. And our awful treatment of ourselves (for example in totalitarian societies) is tied to our being subsumed in something greater.
There is a long and complicated history in English speaking people of "rights for me, but not for thee" which started with the king, was broadened to nobles with the Magna Carta, was broadened to rich landowners with the establishment of Parliament, was in the process of being broadened to free white men around the time of the American Revolution and has piecemeal been given to other groups over time.
What today we consider "universal rights" were historically not universal. Our awful treatment of others is tied to our not granting rights to them. And our awful treatment of ourselves (for example in totalitarian societies) is tied to our being subsumed in something greater.