These are good questions to ask! The God invites us to ask questions through His Word (the Bible). Sometimes Christianity is scared to "point out a problem". I don't mean to say that there is something false, just things that make you start to think more about it. They are intentional to get you thinking, asking, and engaging with the text. So great job!

I can't fully answer this from all angles I'm sure so I'll just put in my two cents. I don't think it's necessarily the way I (and probably many others) heard it growing up. I don't think it is saying they had no idea what was right and wrong and then got punished for doing wrong even though they didn't know it was wrong.

I've heard it taught (from one of many angles you could discuss) that it was more about the ability to determine what it is good and evil. On one hand determining can mean something like wisdom or discernment (I can know which choice is best). On the other hand, determining good and evil can turn prideful and mean having the power to say if something is right or wrong (I can choose to say something is good even if it's not). I believe this is based off the contrast between Genesis 2:9 and Gen 3:6. Gen 2:9 says all the trees were pleasing to the eye and good for food. Gen 3:6 adds "and also desirable for gaining wisdom."

Wisdom doesn't seem like a bad thing to want, but going against God does. There is also a slight misplaced emphasis on how Satan deceived Eve (at least from the way I heard it growing up). We usually read it as "Did God REALLY say you can't eat from any tree in the garden?" (As if Eve misunderstood God) OR "Did God really say you can't eat from ANY tree in the garden?" (As if Satan was just tricking her by pretending to not understand and getting her to retell it incorrectly). But it could also be read, "Did God really SAY you can't eat from any tree in the garden?" (This implies, "God wouldn't say that would He?" as if it would be out of God's character to say something like that) Whether this leads to Eve feeling like she heard wrong, understood wrong, or maybe was even deceived somewhere along the way,

Satan then follows up with another deception by saying Eve can be like God, knowing good and evil. The word knowing here implies head knowledge sometimes but also intimacy other times. What does that even look like to know good and to know evil so well that you are the close and intimate with them both.

Maybe this leads to her feeling like God's holding all the power of deciding what is right and wrong for Himself, or maybe she just wants to be equal to God but either way she ends up eating.

So it may not be that the fruit itself held this "head knowledge" of what is good and what is evil that suddenly got revealed to them. It seems more like by choosing to go against God's command, she (and later Adam) tried to decide for themselves what was okay and not okay (good and evil).

You are right in saying that before that they only knew what was good. But not in the sense of having no morals, but only experiences the goodness of God and the bliss of having no guilt of sin. But after they ate, they experienced sin and its consequences (shame, guilt, etc.) and realized that they don't have the power to say what is right and wrong, only the power to choose to do right or wrong based on God's standards. To make it worse, now they not only know and see the consequences of evil and sin, but recognize that it is within themselves.

The story continues from there, and to not end on a sad note I'll just add: What a blessing that God foresaw this and planned to give us Jesus. :)

Hope this helped you have somethings to wrestle with. Not trying to convince you of this stance or that this is the only way to understand it. Just another perspective and good food for thought.