In case we did not know, New Scientist confirms that at the base of the (postulated) tree of life is an extremely complex life form, much like a modern cell.
“There is no doubt that the progenitor of all life on Earth, the common ancestor, possessed DNA, RNA and proteins, a universal genetic code, ribosomes (the protein-building factories), ATP and a proton-powered enzyme for making ATP. The detailed mechanisms for reading off DNA and converting genes into proteins were also in place. In short, then, the last common ancestor of all life looks pretty much like a modern cell.”
It is easy (or not) to imagine something as simple as that arising by natural processes.