The origin of life has several promising hypothesis on how life came to be on earth. With the RNA world theory the idea is that RNA kept randomly forming pairs and one of those pairs was able to replicate and then replicated in a exponential function. This video explains the RNA world hypothesis: https://www.youtube.com/watch?v=K1xnYFCZ9Yg&t=11s
The Origin Of Life
Dusty’s Bio Blog 