Conflating right and wrong with good and evil misses the point of Genesis.
One can be wrong (incorrect) without being evil. One can be right (correct) without being good. Eating the fruit was not about having the ability to distinguish right and wrong, but good and evil.
Adam and Eve knew it would be wrong for them to jump off a cliff (or out of a tree), eat a rock, or breathe in water. They knew it was right to drink water and take care of themselves. This is Instinct and having nothing to do with any psychosis. We can imagine God telling them, "Don't breathe water, jump off a cliff, or eat the fruit from that tree in the middle of the garden" and Adam and Eve following these instructions. Animals do not know good from evil, but they are not psychotic, because they have an instinct of what is correct (right) and what is wrong (incorrect).
The fruit of the tree in the middle of the garden contained the knowledge of good and evil--how to create good out of evil...and evil from what is good. There is, in Jewish thought, the idea that the reason Adam and Eve were given this command was because the fruit was not yet ready for consumption. For that reason, Jews do not eat the first produce from a young tree. They wait until the second year.
