That is true that Medicine person/Shaman (man or woman) were not perfect in diagnostic or treating Native person. It is now hard to find Medicine person or Shaman to give us right medicines that came from plants and trees to make us feel better. They also performed praying and using ritual tools to try to cure us. It is our health.
I don't remember knowing if the medicine person or shaman do the circumcision for the baby boys or very young boys. It was never known to perform that. I would have to ask if I get to see the Medicine person or Shaman about it. If I am lucky to find one that knows how to treat people with special medicines.
Also you are right that doctors are not Gods
. They are much humans as we are. No one is perfect. That is true.