They arrived here the first time 20,000 years ago, and a second wave 10,000 years. They crossed over from what is now Russia into Alaska. They probably came over in tribes of about 50–100 people. That’s not a lot of dna to pull from to form an entirely new peoples.
Compare that to the human history of Europe which started about 45,000 years ago and had a large genetic population to pull from, and a lot of different peoples with a lot of different ideas to come into contact with.
It was the Spanish who brought the horses here, in the 1500s. Some of the ships wrecked and the horses swam ashore.
At one time Europeans were motivated to live at one with nature, because that’s all they knew. Up until about 1000 years ago, that’s all any of them knew. After that, only a few knew about modernization.
You’re idealizing the Indians to be some sort of spiritual dreamers. They are humans and if they had come upon a discovery that would help them live, they would have taken it. And they did. In fact, they discovered Casinos!