People: Mythical Transformation to Animals

I researched a tribe, or group of people, that are known to follow a religion called Shamanism. These people worship two idols: the Creator (or God); and a mythical character, who acted almost as a prophet for the religion. A belief of this people is a myth (or so the rest of the world thinks) that states that the world was full of people at one time, and that the majority of them were transformed into animals. For this reason, these people feel a close bond with animals because of their shared human ancestry (before the transformation and now). The way that this bond is exhibited is through rituals that the people commonly practice involving the simulation of animal behavior. This is the explanation of the myth believed by the people of Shamanism involving the transformation of people to animals.