How do you know that their souls have not just been implanted from God, into their bodies, any time all the way back to conception? Implanting, not formation.
I don't profess to know anything, you do. I'm agnostic remember.
My best guess at the moment is that our conscious mind is a beneficial tool for survival and propogation of our genome. That in itself to me is beautiful and poetic and gives meaning to my life, that I am merely a small link in a much bigger chain and we are all connected from an information perspective. The religious books are all written quite tyranically, as if the reason for their writing was to cause man to fear one another.
To me "emergence" has much more poetic beauty than "creation", plans and blueprints, so linear and synthetic. And then who created the creator etc etc.
Of course if evidence were presented to me that would suggest otherwise then I would be quick to change my opinion, I keep an open mind. For example we all might get a popup window in our vision tomorrow saying "you are in a simulation", if that happend then it's something one would just have to deal with.