This question consists of two parts: (a) since Adam and Eve were placed in a separate place from what we regard as Nature, there is a great difference between the Garden and the rest of this planet. Evolution, if it means time related events, would apply outside of the garden, but not within it. (b) Once Adam and Eve made the wrong choice, they were driven out into this earth, and they were in need of redemption. Milton sees this as loosing paradise.
If we close our minds to this distinction, than we are left to make up all sorts of narratives.
Now if we also assume that the entire creation was the garden made for Adam and Eve, we indulge in error - it is clear that they were driven out of a place of comfort and well being, and into a place of hardship and pain. It is also clear that they possessed knowledge of God, and yet the story shows us that human nature distinguished itself through sin, debauchery, murder, and so on. So redemption is directly related to the Mercy of God and is an act of Grace by Him.
Your remarks also touch on what God may know from eternity to eternity, and also theodicy. If God knew before hand, why did He do this instead of that - so to speak. I see this as human beings acting as gods, in that we know more than God, or can show God, what is good at one time, and bad at another.However these questions have troubled us all, and some turn away from God as a result, while others understand why Mercy and Grace are central to the Faith. Obviously it is impossible to discuss these matters in detail within this context.
On the rest of humanity since Adam, I think we may infer from Genesis that other human beings were made aware of God through Adam and his descendants. As Paul says in Romans, until the Law came, we may be unaware of our sin, but once it does, we know that we are condemned and we need to turn to Christ for forgiveness and salvation.
Now on questions regarding our physical make-up and our capacities, I cannot see why biology, and the rest of the Sciences, would not inform us - these are outcomes of human intellect and the human spirit - and also distinguishes us from the rest of the created order, in so far that human agency can and does change that order.