3. Panspermia
The Panspermia hypothesis proposes that life, or its essential components, originated elsewhere in the universe and were transported to Earth via celestial bodies such as comets, meteorites, or cosmic dust. (astronomy.com) This concept suggests that life is widespread throughout the cosmos and can be distributed from one planetary system to another. (en.wikipedia.org) Variations of this theory include naturalistic panspermia, where life arrived on Earth by chance, and directed panspermia, which posits that intelligent extraterrestrial beings intentionally seeded Earth with life. (ebsco.com)