Look at the Fundamentalists get their panties in a wad as someone points out the biggest hole in evolution. How did it start. You used to say it was a primordial soup until some scientist figured out that was completely impossible. You guys are so amazing with your level of faith in a myth.
What?
Geological evidence suggests it took nearly four billion years of evolution, from the simplest organic molecules until the great Cambrian Explosion of multicellular critters.
So no scientific theory can reduce four billion years to a few simple sentences of explanation.
But organic chemicals which replicate themselves imperfectly under certain conditions seem a pretty promising place to start looking.