Adam and Eve were told to stay away from the forbidden fruit, but they ended up eating it nevertheless
There began the human nature of making mistakes, and till this day onwards people still make them
Mistakes were not supposed to be forgotten, if that were so, the whole point of it ever existing is pointless
Adam & Eve learnt the lesson of obedience. Just like that every mistake teaches us a lesson, a lesson we need to embrace, so that we can further avoid repeating them, or prevent someone from repeating it
I'm not ashamed to admit that I've made more than my share of them, but even more proud to admit that I've learnt more from it