So in response to this question
Indeed, did Adam and Eve ever reject anything? Is defiance itself a rejection, or is it merely a focus on autonomy, a want of freedom?
I think the answer might as well be “yes”, they rejected something – at least their nakedness and
being found by God.
I think I feel the tension you’re pointing out, though, insofar as their curiosity seems hardly blameworthy, and faced with two people (God and the snake) confidently telling these seemingly intellectually dependent humans two conflicting things, it doesn’t seem too egregious to have gone with one over the other.
So I think it’s pretty important to remember that (per St. Thomas) whatever words we use to say something true about God’s actions or attributes, those words have a very different meaning than when we use those same words to attribute actions or properties to created beings. God doesn’t ‘tell people things’ the way humans (or, presumably, prelapsarian snakes) do. So we can imagine Adam and Eve knew there was a big difference between God and the snake, and that going with the snake’s version was going
against the true version, even if some wishful thinking might have gotten them to deceive themselves about it a bit.
To be clear, I don’t think that means they were blameworthy, though I guess it’s tradition to think they were. I just think it brings into a nice functional package the two kinds of rejection: turning away from what you know to be true (in the sense of statements, propositions, etc.) and rejecting in the ‘finding it unacceptable’/suffering way. Namely, the first kind of leads to the other, and desires can lead us to weaken our commitment to the truth in the first place. And (maybe) staying firmly on the side of truth, accepting what is given, and so on, is sufficient for avoiding the second kind of rejection that leads to suffering.
So I don’t know if defiance, in the sense involved in going with the snake’s rather than God’s version of the causal structure related to death and the tree, is itself a rejection (of that latter kind). But it’s at least intimately tied to it. And if union with God just is what God gives us when we open ourselves entirely to Him and His creation, then maybe, sure – maybe then turning away from God’s account of the causal structure related to death and the tree is itself a rejection of the second kind, though it isn’t conveyed as directly. Maybe it’s turning away from union with God, immediately causing a feeling of separation, anxiety of self-reliance in an uncertain world, and dissatisfaction because of our limited powers and unclarity about what is good for us.