Sure. This is how everything works. I don't believe in Cultural Appropriation as a thing since Culture is just ideas. Cultural Appreciation is very much a thing though. It is how good ideas, and yes bad ideas spread from one culture to the other.
The Native Americans had a lot of different tribes and a lot of different practices just like everywhere else in the world. It wasn't all good. I say this as a person with a significant amount of Native American ancestry myself. I have quite a bit of Cherokee, and Chickasaw in my ancestry. My Step Father had Choctaw as well. I don't claim that one because it is not in my DNA.
There were some really good ideas. There were also some tribes that were pretty negative. It wasn't all peace. Yet there were definitely tribes and regions that were better in this regard than others.
RE: Is it a Democracy? Nope. Is it a Democratic Republic? Nope. Is it a Republic? Technically... maybe.