I read the story of Adam and Eve with symbolism. Because we know Satan was the snake, that means there is symbolism attached and shouldn't be read like they ate a literal piece of food and thus, sin came into the world because Satan isn't a literal snake, he's a Cherub.
I think problems arise when people try and read the story of Adam and Eve literally. Like, the idea that God placed a literal tree in a literal forest and said "don't eat that one", like a massive temptation beacon. If God is holy, and scripture calls us to be holy as He is holy, and scripture tells you NOT to create "stumbling blocks" of temptation for other people (Paul talks about this constantly and Jesus gives the idea of throwing temptation in front of a child, that its better for them to be tossed in the sea with a millstone around their neck ), then how are you supposed to read the story?
I have a huge study on this, but I'll sum up... The garden wasn't really a garden, it's the Temple of God. The tree, wasn't really a tree, it's a scroll of knowledge and Adam and Eves job was to tend God's Temple. If you look at it from that point of view, it would make sense why God would put something in His own Temple, but tell them NOT to read from it (ingest like food) or they will die. It also makes sense why God then warded it off and protected it, lest they become immortal (without repentance, without the aid of God, etc) because of the information. Also why the Torah is called the Tree of Life.
But simply put, what sin did they commit? Disobedience. God told them not to do it, they did. That's all there is to it.