I believe if life is common than there must of been at least one group of aliens that at least attempted to colonize it self everywhere in space?
Unless humans are a extreme anomaly and that most other aliens don’t really care about space exploration, and just focus on their home planet.
I love this stuff. I kind of like the protein world hypothesis, which posits that in primordial seas rich with organic matter some simple peptides form and, over the course of incomprehensible amounts of time, combine together such that they become self-replicating. Though AFAIK the RNA world hypothesis is more accepted.
https://en.m.wikipedia.org/wiki/Abiogenesis