I believe that God created things, including life forms. It's not necessary to also conclude they must never change, as we see with selective breeding. And it had to start somewhere. At some point there had to be a life-form with a genome, able to survive, acquire nourishment in whatever way, and replicate itself to some extent so as to split into more than one cell. Basically the irreducible complexity argument. The mechanics, just what the time frame was, I don't know. As for the big bang, well, I hold God said 'Let There Be Light,' and I would imagine the BB would be a major light show.
It's worth mentioning that the Bible is a guide book to the meaning of life, not a manual of its biochemistry/physiology. It introduces us to God, and a larger framework of creation into which mankind falls in the Christian system. That doesn't necessarily mean all creation centers solely around us. While it lays out an order of creation, I think 'who & why' is the more major lesson than the exact time frame/mechanics of how. There are some holes in my understanding I just have to accept, just as scientists have to tolerate holes in theirs for awhile.