I think ancient writers tweaked most of these old stories to improve their emotional and moral impact, and that's OK to a large degree. These truths are necessary and keep our societies healthy. Mythology is not about literalism, anyway. These stories are about carrying a core and essential archetypal truth forward using literature as a vehicle (even the Biblical stories) to the fundamentalist's horror.
There's a story about George Washington (our first US president) chopping down a cherry tree as a child. When asked if he did it, he could not tell a lie and instead told the truth, the consequences be damned. He was revered for doing so.
Now, did these events literally happen? Probably not, but the moral of the story punched through the fictional account and taught me a valuable lesson about honesty and integrity, and I lied perhaps a little less as a result. I still remember that story as clearly today as when I was a young boy.
Paul, a Christmas movie called The Nativity Story, based on the embellished virgin birth story you clarify, moves me like no other Christmas movie. It's a fantastic adaptation that (to me) perfectly captures God's truth. I watch it religiously (pun intended) every Christmas season.