Of course, that's why I am an atheist.
Your suggestions for possible reasons that the story of the virgin birth came about is missing on gigantic possibility: somebody lied. I 've seen a joke along the lines of if Mary was really a virgin, why did three men show up with gifts.
I am a firm believer in Occham's razor.

Fair play to ya but why do you read the bible? Life's short

The Virgin Birth was not the birth of Jesus, it was the birth of Mary, who was born without the taint of original sin, so she could be pure enough to carry the child of God.

From what I have learned this idea was one that used misinterpretation or even a cover-up to promote an idea of a miracle. It was said the original idea was that a virgin will get married and give birth. The get married part was eliminated and we all know how that ended up. My question is what kind of fool was Joseph? He was not privy to the angel whisperer and his wife became pregnant and the marriage had not even been consummated yet (does that nullify the marriage, should she then be stoned?). I find it incredulous that so many fall for this nonsense. Unfortunately, those of us growing up, Christian did so ourselves until some angel whispered in our ears?!

The idea of a virgin birth was a common one and the Christians only took another page from the book of mysticism's'.

Mary was a bit of a tart and told a lie to stop her being thrown off of a multi-story carpark and everyone believed her.