We believe our spirits ( our intelligence combined with spirit matter) were born in heaven. Later Adam's physical body was made from the dust of the earth and through the process of procreation we are all the children of Adam and Eve as well. We believe that it was our spirits that fought in the war in heaven against Satan and his minions before coming to this earth. One of Satan's and his minions punishment for their open rebellion was that they were denied receiving a body of flesh and bones on this earth and in the hereafter.I understand...faith based on logic and reasoning. It still stands that that it is all shrouded in mystery and supposition.
Genesis says God made man out of the clay of the earth and breathed life (spirit/intelligence) into the first man. I see the power of God in this, so much power, that life and intelligence flowed from God to the first man to all his descendants.
While again it is supposition wrapped in a mystery, our spirits may have been birthed here along with our bodies. I am equally divided between the two possibilities. Mystery. I don't know which is the reality.