It is easy to accept, sure (If I know what you mean, and if I do, that something is easy to accept doesn't mean it's rational, or even likely. For example: Starting from nothing, i.e. if you think of a group of people who have no existing societal/familial influences, it's very easy to believe that the spirits of the dead live on in nature. But this is not rational or likely). But you can call it rational or not, and while as I'm sure everyone who's participated in this threat for very long is aware, and as you appear to reference indirectly, there are some milestone experiments done on the subject, but I daresay that what you would like is something along the lines of complete certainty, and according to that standard, it isn't known, this change between when there was no cellular matter and when there was.
But this certainly doesn't lead to any (unspecified) designer-being.
Secondly, there's nothing about the group of solutions, so to speak, which do not involve god-like beings, which would require them to be only imagined, if that's what you mean.
Thirdly, you would appear to be one who wouldn't think much of an idea if it isn't already (completely) known. But even several decades ago the infinite space of solutions to the problem had been narrowed down considerably, for it was found that all of the complex molecules that allow for life could be produced from elemental (or near enough) substances, when said substances were put under electric current. Incidentally, those elemental substances were likely the composition of the early earth's oceans.
