It's worth pointing out that panspermia (life arriving from elsewhere in the universe) is a perfectly valid hypothesis - we already know that life can survive a considerable time exposed in space, and that life can also be found deep inside rocks, so it's conceivable that simple extraterrestrial life could have survived in a meteorite to seed evolution on Earth.
It's not a mainstream hypothesis because the timescale involved in travel from another star system would almost certainly be far too long for DNA or RNA to survive intact. It would be far more likely to survive a trip from Mars on one of the many meteorites that have come over, but that still begs the question of how it arose in the first place.
But there is a mainstream hypothesis involving the deposition of complex organics (the 'building blocks' of life) from space, where they (and water) appear in abundance. But, AIUI, these complex organics could also have been generated on Earth, so such material from space would only be significant when falling in areas where conditions were not suitable for the native assembly of complex organics.