The first problem with what you know: there were many different tribes and they didn't share common culture. They did have some trade, but there was no unified culture.

Second problem: diseases (smallpox is the best known) spread much faster than the Europeans and so most of what we they could see was influenced by large numbers of dead people in the previous generation that wasn't recovered from. It is a lot easier to be peaceful with your neighbors when there are no population pressures (that is everyone can eat enough on the land you have). Likewise it is easier to give away "stuff" when you have a lot of extras from older generations that nobody needs.

Third, guns and horses allowed for ways to life that were not possible before. The great nomadic horse tribes - that was clearly observed, but the way of life depends on things the Europeans brought not long before. It is really hard to know what the culture was like before the horse arrived. There is reason to suspect that those great nomadic tribes where heading to a population collapse of the bison herds because the horse and guns enabled over hunting (but of course Europeans arrived before that could happen, and did their own number on the herds).