My answer would be in what follows, but since I arrange things bit differently, I do not address your question directly.
Honestly, to view Adam as the cause of sin seems to me a distortion of what has occurred.
I do understand that it is how you are conceptualizing the Genesis story, perhaps this will help with your search.
In thinking about the logic of Adam, I start from the ontological reality of Adam in this world:
- I am a expression of humanity.
- The complete/whole “man” is Adam.
Contemplating where we are here and now,
what is an undeniable reality is that
we find ourselves in a state of sin, within and without.
We are broken within ourselves and in our relationships with the world, each other and God.
God who is Goodness, did not create this evil world,
it is what transpires when we damage our relationship with Him.
This is the reality in the moment, but we exist as temporal beings.
Who we are ontologically had a beginning.
As we are persons, there had to be an original person.
As we are persons in relation to one another as children of God,
the first person had to exist in relation to another child of God.
God did not create two separate persons; He created two (Adam and Eve) from the first (Adam).
We exist as our individual selves but also as community, as a Church.
We think in thoughts and symbols whose basic nature is communication.
These words and images evoke ideas in the other.
We share common human feelings, and each in our particular way, the same gifts.
With respect to God, we are meant to share in His love.
By obeying in Eden, as does the Son in eternity,
we would have been elevated to eternal communion with Him.
This did not happen as we chose otherwise, but
through the incarnation of the Word, we can truly call God our Father.
The Word:
- is the whereby we were created
- speaks to us in history
- established His Church on earth
- created the way for His coming, which
- reveals through the cross and the resurrection
- how in eternity, the Lamb was slain at the foundation of the world
- thereby redeeming and saving humanity
Man in Adam became broken by turning from God.
We are in Christ brought into the loving filial relationship that is our fulfillment.