I see the story of A & E as the story of the first people to feel a sense of self responsibility and awareness of themselves and what we think of as " being human"
The ability to reflect on our death and awareness of our mortality. Our ability to control our environment, farming, etc.
This assumes other animals don't reflect on these things. They might, but they don't do, as we do.
There probably was never a literal Adam and Eve, but there might have been a growing awareness among a small group of families.
The story of Adam and Eve to me symbolises mans evolvement from the other animals, to become self aware and capable of enormous change to his environment.
The ability to interfere with the natural order to benefit humans, our creativity and desire to explore.
In that sense the story is credible to me.
I'm prepared to accept other primates may exhibit some of these qualities.