There is an interesting theory that a gradual process of increasing complexity of autocatalytic processes might be more probable to lead to something like life than a sudden abiogenesis event and that there might have been no single event that could be called the beginning of life.

Here is an (accessible?) article on it:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843823/

One of the authors (Addy Pross) even wrote a book called What is Life - How Chemistry becomes Biology about this idea (https://www.amazon.de/What-Life-Chemistry-Becomes-Landmark/d... ). There's a review of the book at this link [PDF]: https://www.pagepress.org/journals/index.php/eb/article/view...

There's a very interesting book called "What is Life - How Chemistry becomes Biology" [1] by Addy Pross (homepage: [2]) in which he claims, among other things, that there is no clear boundary between chemistry and biology.

Here's a review if you don't want to go hunting for information on it [PDF]: https://www.pagepress.org/journals/index.php/eb/article/view...

[1] https://www.amazon.de/What-Life-Chemistry-Becomes-Landmark/d... [2] http://www.bgu.ac.il/~pross/