Be very careful, you're trying to think for yourself. The answer to almost all questions is - God moves in mysterious ways.
That is a really great question you have posed, one that has me scratching my head as well. If you are a member of a fundamental belief system then we have creation and an immortal soul from the get-go. Except for a few who believe in a mortal soul. I believe that science is the very equal of religion in searching for the intangible aspects of existence - so I believe that evolution in some form is a fact. I believe in an evolution that is under the guidance of whatever stops the universe from flying off into disassociated atoms.
So, when did we become issued with a bullet-proof, unlimited warranty soul? Humans are so stepped away from the rest of the animal kingdom that it is impossible to believe we are as we are without a purpose. All animals have a life force, come soul, I think we have an extra essence or spirit that is immortal. Not only immortal but containing our life experiences, learning and our personality. We progress in this life so it would be strange not to work towards some form of progression in the next. So an immortal soul could have been present way back before we became anything like modern man. Or it could have been a reward for finally understanding that there is One Essence (one God) that enables all the dimensions of existence. Or it's all just an amazing coincidence and we'll all be as dead as maggots one day.
