The scripture does describe Christ as the head of the church, just as a man is the head of the woman. And the meaning of it all is very much as you have described. For the relationship between husband and wife, the man is the ‘head’ in his leadership or authority in the relationship and as the biological origin. Yes, they are not one biological person where Adam is only a physical head, but the idea is to be cast upon the one person that results from their mystical union. Adam is the symbolic head on top of the body which is Eve.
As leadership and authority over the body comes from the physical head, so in a mystical body Adam was a head, and Eve was his body, which he was to take care of and nourish. She was to support the head in a cooperative role. Together they were one person. At least this is how the New Testament understands the biological symbolism that was created so to reflect and run parallel to the spiritual truths analogous to it.
the Head, from whom the whole body, nourished and knit together through its joints and ligaments, grows with a growth that is from God. (Colossians 2:19, ESV)
Rather, speaking the truth in love, we are to grow up in every way into him who is the head, into Christ, from whom the whole body, joined and held together by every joint with which it is equipped, when each part is working properly, makes the body grow so that it builds itself up in love. (Ephesians 4:15-16, ESV)
This idea of nourishments from the head and organic life sharing of the body is similar to the 'living' temple imagery where Christ is the cornerstone of the building and the Spirit flows through each 'living' stone. Yet it goes beyond a mere handy symbol. The headship of Christ is meant to imply a real ‘mystical’ union in the Spirit, where we are truly members of Christ’s physical body, as we once were members of Adam's humanity (extended body).
Just as Adam’s 'material' was provided to make Eve, and then Adam and Eve literally joined through sexual intercourse to duplicate 'their material' to form children, all of us are from Adam. (We inherit his guilt and sinful nature by this means as he was our federal head). In other words, all humanity is Adam’s body and he is our head. The whole gospel is premised upon this idea, where Crist is a new federal head of a new creation in him. When a person is 'born again' through the 'seed' of the 'word', the Spirit unites them into the human nature of Christ, first mystically, and then organically in the final resurrection. By this real mystical union, our old life in Adam literally mystically dies and our new life is born. By being made ‘in Christ’ we are like a seed dying and becoming new. Our seed dies by being killed and engrafted into a new 'life form' (Christ). Thus we transform and we are removed from Adam, being planted into the new Adam, i.e. Christ, our new Federal head. This is not just a handy symbol but also a mystical reality.
In the same way, my wife is my body. Although the organic part is not true like Adam and Eve, by sexual union the symbolic acts underlines a spiritual truth. She is me, without doubt as we have become 'one flesh'.
In the same way husbands should love their wives as their own bodies. He who loves his wife loves himself. For no one ever hated his own flesh, but nourishes and cherishes it, just as Christ does the church, because we are members of his body. “Therefore a man shall leave his father and mother and hold fast to his wife, and the two shall become one flesh.” This mystery is profound, and I am saying that it refers to Christ and the church. (Ephesians 5:28-31, ESV)
The fact that this mystery is ‘profound’ speaks to the incomprehensible ‘mystically literal’ reality of our being in Christ and dead to Adam. The nourishment in love references made earlier indicate the holy Spirit in the union. There are only two people we can be in the body of, Adam, or Christ. Inwardly by faith we are created in Christ, while outwardly our life that came from Adam is still dying and will be joined to Christ later. Then nothing about us will be in Adam and all our being will be in Christ, our life will be his, which explains why we will lose our ability to sin in haven as our life can't break out of his life.
If we try to pierce the veil of this mystery to any degree (of course we will mostly fail) I think the following versus are a good place to try:
He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. And he is before all things, and in him all things hold together. And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent. For in him all the fullness of God was pleased to dwell, and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross. (Colossians 1:15-20, ESV)
From this strong set of versus we can see some principles that apply:
- All God’s life originally comes from God, of which all other life
- All this eternal life and attributes of God was communicated to the man Jesus through the incarnation, as a repository and treasury for the life and existence of a new creation – no longer derived biologically or spiritually in reference to Adam and his sin.
- Upon dying for sin, this God-Man enabled a means to kill us and our sin. He created a legal means to make us alive. By bearing our sin and imputed his perfect obedience to us, we can be mystically united to both his humanity and fellowship with his divinity.
- God by his Sprit draws men to believe in His Son and through the mystical union transfers the debts of sin upon Him and his righteousness upon them.
- Christ an the new federal head is the Lord over creation, so that even with respect t his humanity, the universe is his possession obtained for us forever.
This joining of men into his flesh is an eternal, irrevocable literal joining of their souls into the life of God deposited in Christ. Just as it took a new Adam to transplant us into a second Adam, it is impossible that we then can be changed again, without a third Adam, with the same powers of Christ. This never shall be as the Father is perfectly satisfied in the works of his Son, to be Lord of the new creation forever and ever. It would be easier to explode the entire universe then to plant a Christian back into Adam.
John Own is good for explaining the mystical aspect of this union in various locations of his theological works:
He gives and communicates unto them his Holy Spirit;—the Holy Spirit as peculiarly his, as granted unto him of the Father, as inhabiting in him in all fulness. This Spirit—abiding originally as to his person, and immeasurably as unto his effects and operations, in himself—he gives unto all believers, to inhabit and abide in them also, John 14:14–20; 1 Cor. 6:17; Rom. 8:9. Hence follows an ineffable union between him and them. For as in his incarnation he took our nature into personal union with his own; so herein he takes our persons into a mystical union with himself. Hereby he becomes ours, and we are his. (John Owen’s Works, Volume 1, Page 365)
Conclusion: Yes, you have it all right, I just do not know why you seem to pause and doubt it. Your question already outlines what Christians have believed for centuries as far as I can tell.