Otherkin

Otherkin (or simply kin for short) are people who identify spiritually or psychologically as nonhuman. These identities, or kintypes include but are not limited to: creatures and plants on earth both living and extinct, otherworldly beings, and forces of nature

There are both spiritual and psychological explanations to otherkin. Spiritual otherkin may believe that their soul is nonhuman or that they were meant to be reincarnated as nonhuman. Psychological otherkin may believe that their kintypes are a result of a conscious or unconscious coping mechanism or that they are mentally closer to their kintype than human.