No Cofty, I don't believe the spirit or life force in a living organism is mysterious at all. While all the processes in your body function as they should, you are alive. When one or more fail, you die. God is the source of life in the sense that he originated and kickstarted all the processes that sustain life. The organism must take it from there, supplying nutrients and water to keep the said processes going.
I go for the rule: Life begets life. In addition, man has been bequeathed with a magnificent brain, superior to the animals. In that sense man was made in God's image. If God could create life, so could man. It's just a question of time. The question is: Would he be allowed the time to do it?