The Hindu Dharma believes in rebirth. According to the scriptures; just as we discard old clothes and wear new ones, our soul leaves the old and aged body to take a rebirth in a new body.
Please note that we wear clothes, the clothes don’t wear us. Similarly, the soul dons the body not vice-versa. Just as I exist even after I discard my clothes, the soul exists even after having left the body. The soul never dies. It lives before donning a body, it lives in a body and it continues to live after it departs from the body. The body takes birth and dies, as it is temporal. The soul is eternal. It will never take birth and never die. It always exists.
After death the soul takes on a new body in accordance with its destiny or past karmas (deeds) or as per its psychic state at the time of death. Just as King Bharat was reborn as a deer because of his attachment to a deer at the time of his death, and Nrigraj was reborn as a python for the same reason.
As long as an individual does not burn down his physical, subtle and causal bodies in the fire of knowledge, he will continue to be reborn in new bodies and it might not necessarily be a human birth.