Probably something like that, yes. Real stories about one person or many people that slowly coalesced into what we'd recognize as the narrative seen today. Real to a point, but the truth being far, far more mundane.
Of course, it could also all be literally true. That's not impossible. It's just also not terribly likely.
I'd like for you to know, whatever differences we undoubtedly have, I have more respect for your admittance to simple truths(that there simply is no hard evidence, or likely would/could ever be for the likes of Abraham and such), while still believing, than I do for countless others who either simply believe it all or believe none of it.