These days we have an industry that makes DNA "oligo"'s that should be somewhat close to how life would have looked at some point in the distant past. The chemical reactions involved in the entire lifecycle are entirely understandable with university chemistry knowledge. Starting the reactions takes a remarkably small number of chemicals present, and none of these are too far fetched.
You have to keep in mind that, on earth, today, life cannot just exist. It must compete successfully with other very complex lifeforms. This effectively imposes a minimum complexity level that any lifeform must attain to survive in the current environment. But, conceptually, there are many things that would count as life even though they have zero hope to exist on earth (outside of labs). Such simple lifeforms today can only exist in places like the clouds of Venus.