I think it is the jump from the raw lifeless materials to the very first life form that is difficult to explain, not once it got going.
Once you have algae or whatever came first, the rest isn't an issue IMO.
It's inanimate matter to something else that puzzles me.
Scientists won't know for sure life's a fore gone conclusion that given the right conditions life will form until they find some somewhere else.
They don't yet know it exists elsewhere yet, not for sure 100%
Although I reckon it's pretty certain it does.
There is a parallel with when Victorians first came to see that humans were part of the animal kingdom. They struggled to grasp this, as it seemed so obvious that humans were radically different from all other animals. Noone had seen chimps building steam engines or gorillas debating the rights and wrongs of slavery. There was such an apparent gulf between us and other apes. Now of course we are filling in those gaps, hardly a year goes by without some paleoanthropologist digging up yet another ancient human ancestor and we come to understand the apparent gulf as a result of the extinction or amalgamation of all the intermediate species.
Maybe we are at a similar point in history now with regard to our understanding of life; we tend to see a huge conceptual gulf between animate and inanimate matter, but that is likely just down to the happenstance of where we are at. The common distinction between life and non-life is really a superficiality, in reality there are degrees of life-likeness, and if there is an apparent void between organic chemistry and simple biology, it is because many intermediate forms are no longer present on this planet for us to observe; it is down to the rampant promiscuity of carbon, that compounds of intermediate complexity have all now been swallowed up into the more easily recognisable forms that now today constitute me and you and every living thing. We can't dig ancient carbon compounds out of the ground though, we have to use other methods to infer what pathways might have led to life on this planet.