A medicine man is a traditional Native American healer. Healing was only part of their function. Another part of their role was as guardian of their belief system, and their rituals.
A very similar role was played in many other mesolithic and neolithic societies, such as pre-modern Africa and New Guinea. This person, man or woman, might help cure physical, mental, or spiritual health problems. A term such as shaman or witch doctor reflects the supernatural element in such roles.