How was it possible to have this "rationalness" prior to consuming from the tree of knowledge? They simply wouldn't know any better and have no concept of consequences. How can you actually reason without knowing shit? Sure, god told them they would die, but how would they even know what death means? The humans had no prior experience with death up to this point! No human/thing had ever died, it was just them. It would be super abstract. Ever explained death to a child without actually showing them something dead?
And how else would you describe a lesser being kept in a curated garden? Pet seems like an extremely apt term.
Also none of this excuses the omnipotent and omniscient being from being a shitty owner. Why even make the tree if they knew humans were gonna fuck with it? Were they incapable of seeing this possible future? If eating that fruit was original sin, that's a complete abdication of responsibility for: 1) creating the damn tree, 2) putting it in the garden where the human critters can get to it, and 3) creating a literal agent to psyop the humans into eating it. What a colossal fuck up for an all-powerful, all-knowing god. And that's being generous. A more balanced take is that god is fucking evil for stacking the deck against humanity and then blaming them for it, knowing full well what was going to happen.