I think if I could try to tie the whole thing in one woven rope, it'd run something like -
original sin i.e. "the fruit of the knowledge of good and evil": own judgment is equal to/preferable to God's. One's life is one's own, and not God's (free will, free gift). Our state here is not one of guilt, but separation - and in separation, wretchedness. Regardless of "knowledge" of good and evil, our judgment of good and evil yields far from satisfactory outcomes. It is not equal to God's judgment.
Christ is God's judgment pronounced upon us - and upon human judgment. Christ submits meekly to human judgment, and accepts its sentence of death. Then, he lays the penalty aside, refutes human judgement as bollocks, and substitutes God's judgment of us in its place. We can of course reject it, but God's judgment of us is that God judges us worth being saved. God refutes death and refutes human judgment, in the person, sacrifice and example of Christ.
If we trace original sin to Adam, we see how a "perfect man" (at least, a perfectly innocent man) chooses to prefer human judgment to God's, and to sunder his life from God. Christ answers this: a perfect man who is also in fact God, refutes this choice of human judgment as preferable to God's. Through, with, and in him, we find again perfect unity with God. To declare this is the reversal of original sin: to be born again, a gift given back - and our life is now God's, to save and to keep.
Something like that, anyway. All pretty orthodox.
Those who prefer their judgment upon humanity explicitly reject God's judgment upon humanity (Christ).
