A Transfer of Energy

In a 2023 Chinese drama Meet Yourself, the male lead told the female lead that he was an atheist and believed in Science. Then, he went on to say that everything is an energy and will not dissapear; things can only be transferred and transformed; the law of conservation of energy, I suppose which states that energy can neither be created nor destroyed  but can only be converted from one form to another. When the female lead asked if that meant a person can  after death becomes an animal, I had wonder suddenly if rebirth is a transfer of energy...