Who were Adam and Eve?
Adam and Eve were not the first beings. They were the first acceptable versions of the life force that is divine within its nature that can be traced to one strand of chromosomal origins of what you call the continent of Africa. There was a time when hominoid development was interrupted and altered on the level of the chromosome. This genetic engineering has come to be known as the living tree of knowledge, which has trigger points within its evolution.
Language, communication through reason and words, is what separated you from other species, along with selfdetermination. It is your ability to directly reason and make sense of variables and then form those things through reason into a means of communication that set you apart. You are a genetically implanted society that was seeded to advance. Many hominids existed at the same time, such as Cain and Abel. Indeed, this is when Cain went out and was exiled into the Land of Nod and the lower life forms.
Your existence was not a lineal process of singular evolution in which one species adapts and becomes the next level for that species. If it was, then that would still be happening today. This is the problem with Darwinism as a theory of biological evolution: The process does not stop, and if it did, then these species could not coexist. You would have new forms of humankind popping up all over the globe. There are still great apes and other bipedal life forms.