There is the panspermia hypothesis. The idea is that microbial life could somehow be ejected from its home planet by something like a meteor impact. So you have a rock floating through space that contains a dormant single-cell organism. It floats around space for millions of years until it eventually lands on a planet with a habitable atmosphere. The organism evolves over millions of years and eventually, the planet is covered in diverse life forms. That could have happened on Earth. While this theory is interesting it doesn't do much to answer the question of the origin of life. It just passes the buck to somewhere else in the universe.