Study the elements of the story. All was good...all could remain good...but good is not all that is possible to know. Adam and Eve were faced with a choice. One aspect of the story Jews tell, since all in the garden was good, the tree of knowledge of good and evil was good. However, the fruit was not yet ready for them to eat--or possibly, they were not yet ready to partake of this fruit. In remembrance of this, some Jews to this day, do not eat the first year fruits of a young tree.
I grew up with plenty of younger brothers and sisters. This began with dressing them--until the day they announced, "I want to do it myself!" As they grew, there were many more times they announced, "I can do it myself!" I think of this sometimes when it comes to learning the knowledge of good and evil. Could mankind have chosen to learn about the knowledge of good and evil under God's protection, but instead chose to do it on their own?
I come from the position that our ancestors were intelligent beings, noted truths about themselves as humans--and humans as a whole. The truths they learned and observed, they passed on, in simple, memorable story form, to their children and grandchildren, who passed it on to future generations.