If a no parking sign was a "prevention", there would be no such thing as parking tickets.
First of all, as if the event ever happened, but why would God put "forbidden" fruit trees in the garden? Sure, he told Adam face to face. But wait, I thought nobody has seen God because he is spirit? But let's pretend he did. Adam spoke directly with the Almighty God that had just created him and told him, personally not to eat from the tree. You'd think God wouldn't have to paint the curb around the tree red or put a "no eating of the fruit" sign on the tree. One rule, easy, how could Adam mess that up?
But God, for some reason, didn't tell Adam that the devil, whom he already had a problem with in heaven and had cast out of heaven and sent to Earth, disguised himself as a walking, talking serpent and tricked Adam's wife, Eve, or whatever her real name was, into eating the fruit. The woman, that God gave Adam, tricked Adam into eating it also. And then, the all-knowing God pretends that he didn't know what happened. He pretends he can't find Adam. And, then he curses them and the serpent? But, why all serpents? What did they do? And why did God curse all the other animals and plants and the whole Earth? Why? What did they do? Nothing. God just wanted to get back at Adam for not listening? And now, because Adam didn't listen, babies are born depraved and morally evil. All tainted with Adam's horrible sin.
But God's not done. Then he made the Hebrews slaves. That way, he could free them and give them strict codes to live by... knowing all the time they couldn't. Then, after several centuries of futility, breaking all those rules, he tells them that the rules were only meant to show them how wicked they really are. That, they, and all people, are born depraved and are hopelessly wicked and eternally lost, unless.... they do one thing. One thing? That should be easy right? How could we possibly screw that up? Sure God what is it? Believe in your only son and be saved? That's a cinch. Oh, except one problem, knowing how you play the game, God, what's the catch?
Really, no catch? Right, and I believe you. Let me ask you this, God. Why didn't you just paint the curb around your stupid tree red and put a sign around it? And, you could have put a cop or security guard to watch it. And don't tell me you didn't have someone available, because, later, you did have some guy with a flaming sword watching over the whole garden? Why didn't you have him watch the dang tree? He had a flaming freaking sword? Now that would have been a prevention.
And the snake? Oh, I mean the devil in disguise? You're going to have Michael kick his butt later, why wait? Why not back then? In the beginning? No tempter, no temptation, no forbidden fruit eaten. No harm, no foul. But you didn't. Why? You knew all this was going to happen. You knew how right out of the womb how terrible we'd all be. You finally told Calvin how totally depraved we were and that some of us were "chosen" to believe and the rest of us were totally useless, meant for the fire pieces of do-do. You knew all this from the beginning, and failed to mention it?
Or, maybe, this is all a glorious religious myth of how we got in the mess we're in. Along with all the other religious "theories" of what is "truth" and who is "God" and what "objective" morals he wants us to live by. But wait, even if he has a defined set of objective morals, what good would that do? We can't follow them, we're too evil.