This is a Philip K. Dick book. I’ve been a fan of his for years, but he wrote so many books that there are tons that I’ve never read. As is pretty common with his books this one deals with mental illness, and an unstable grip on reality.
The book is set in a colony on Mars, though the planet seems remarkably like Earth. The main character is a man who moved with his family to Mars to try to escape his problems after developing schizophrenia. He started believing that the other humans that he was interacting with were actually dead, and their insides instead had been replaced by androids. In a twist of fate though the teachers in his sons school are androids made to look like historical figures from Earth’s past in an attempt to help the children keep hold of Earth culture.
There are native Martians living out in the deserts called Bleekmen. They are quite clearly based on native peoples on Earth, as well as being inspired by black American history.
Autistic children are kept separated from everyone else in a care home, and a wealthy union boss believes that they experience time at a faster rate than everyone else. He hires the main character to build a machine to try to talk with with a particular uncommunicative child, though he is only doing this to try to advance his own interests rather than to help the children. As the main character spends more time with the child he begins to experience the same events repeatedly.