Should one avoid praying behind a person who believes that the origin of man is animal, despite their uprightness and performance of both obligatory and supererogatory prayers?

The belief that the origin of humankind is a monkey is considered disbelief (kufr) because it contradicts the Quran and Sunnah. One who holds this view is feared to be on the verge of apostasy, though they are not treated as a disbeliever. There is no harm in avoiding praying behind someone who holds this belief; rather, it is appropriate to do so. As for the statement that a human is an animal, this is correct because a human is a rational animal.