One of the important differences between human beings and other living creatures is that, as far as we can tell, humans are the only creatures that are "conscious," by which I mean that we know we are alive and we think about our own thoughts. We judge ourselves and feel embarrassment or guilt for when we judge our own actions harshly. As Mark Twain put it, "Man is the only animal that blushes. Or needs to."
If humans are conscious and other animals are not, and if the theory of evolution is correct (which is another argument for another day), then there must have been a point at which the human race made a transition between unconsciousness and consciousness. And that point of transition would not necessarily have been at the same time we got opposable thumbs, or walked upright.
According to psychologist Julian Jaynes, writing in his book 'The Origin of Consciousness in the Breakdown of the Bicameral Mind," the rise of what we now call consciousness is a relatively recent development in human history, occurring but a few thousand years ago. He believes it is a product of our bicameral brains, which are divided into hemispheres with significantly different functions. Greatly oversimplifying, the right side of the brain is more intuitive (which Jaynes describes as "god-like"), while the left side of the brain tends to be more logical (which Jaynes describes as "man-like"). What we call consciousness is explained by Jaynes as a break-down between the two different functions of the two different sides of the brain, so that the "man" part of the brain began to experience the "god-like" judgments of the other side of the brain.
It is difficult for us now to envision an entire society dominated by unconsciousness, but that may have been the condition of at least part of some ancient cultures, and it is entirely possible that some of the people who were alive at or after the time of the transition would have noticed something happening. Which brings me back to the story of Adam and Eve and the Garden of Eden.
The phrase "Garden of Eden" is synonymous with paradise, but what was it really like? The Bible says that God "planted a garden in Eden, in the east; and there he put the man whom he had formed." Gen. 2:8. But it seems that the man did not have a life of leisure, because the Bible also says that "The Lord God took the man and put him in the garden of Eden to till it and keep it." That’s right, the man had to work. And we know two other things about Eden. First, that God told the man that he may eat of every tree of the garden except "the tree of the knowledge of good and evil." (Gen. 2:17) Second, that the man and his wife were both naked, and were not ashamed. (Gen. 2:25)
When we read the story of the garden of Eden, what we are reading is a story of life without consciousness. The man and the woman have no knowledge of good and evil, and are never ashamed of anything, not even of their nakedness. They work and live in complete innocence, with no guilt, no shame, no fear, and nothing we could call angst.
All that changed when they ate the fruit of the tree of the knowledge of good and evil, for then "the eyes of both were opened, and they knew that they were naked; and they sewed fig leaves together and made loincloths for themselves." In other words, they felt shame. And when God arrived, they felt fear. And when God asked them what had happened, they made excuses. In other words, they were conscious of who they were and what they had done.
So why did God "drive" Adam and Eve from the Garden of Eden? What the author (really "authors") of Genesis are confirming is that consciousness is a very mixed blessing. It brings us understanding of the world around us, and knowledge of good and evil, so that we are more like God. But consciousness also brings us pain. It is why we feel guilt, shame, and remorse. It is why we are often unhappy.
The authors of the Genesis were writing with nostalgia about a time in the not-so-distant past when life was much simpler, and much happier. People lived in the moment, working, loving, and dying. They felt physical pain, cold, and hunger, and sometimes fear and anger, but those were like storms that passed through and were forgotten once the sun appeared again. They never had an "identity crises" or a "mid-life crisis" or regrets about the past or guilt about a mistake they had made. They were childlike, and happy. In retrospect, it must have seemed like living in a beautiful garden, and they must have wondered what happened and why they ever left (or were forced to leave).