Was the "Forbidden Fruit" really just a piece of fruit?

What if in the Garden of Eden, the "Tree of the Knowledge of Good and Evil" was just another tree?  When Eve ate the fruit - it was just a piece of fruit.  It wasn't symbolic for sexual indiscretion.  It wasn't a special tree that caused some physical change to come over them when the fruit touched their lips. It didn't have to be a grape, or an apple, or grain, or a fig.  It wasn't symbolic for wine, or what they wore afterwards to cover their nakedness.

What if there was no magic, no mystical symbolism?  It was just a tree, an arbitrary tree.  The fruit was just like all the rest.

God needed a chance to teach them about obedience, so he needed to make a rule that they could keep or break.
He picked a tree, and said "don't eat from that one."

And that's it.

The only change that happened in the moment they ate the fruit was that they knew what disobedience felt like.  They could now feel guilt.  They now knew a new feeling.  What they felt before was "good," and how they felt in that moment was "evil."

Hence - "The Tree of the Knowledge of Good and Evil" was only special because God made a rule and pointed at that tree.

The "good and evil" part was a natural consequence of choosing to disobey.  They gained knowledge through an experience they had never had before.  They experienced new emotions like betrayal and shame for the first time.  They "fell" from God's presence because "no unclean thing can dwell with God," and now they were unclean.

As always - I don't know.  I'm just speculating.  Maybe everybody else already had this thought.  The entire story of the Garden of Eden could be symbolic.  But it makes sense to me that maybe the tree was just a plain old tree.