As ALL in Adam died so in Jesus ALL live. That's what you're misunderstanding.
Your proposal is certainly plausible, but I believe Paul meant something else. I am taking my cues from his customary practice, employing the phrase "in Christ" to indicate his followers.
Consider the following paragraph from Paul's Epistle to the Ephesians. Take note of the contrast between "those who formerly walked according to the course of this world" and those whom God "made alive together with Christ." And also note the oft-repeated phrase "in Christ", "in him", and "with Christ" and combinations such as these.
Ephesians 2:1-10
And you were dead in your trespasses and sins, in which you formerly walked according to the course of this world, according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience. Among them we too all formerly lived in the lusts of our flesh, indulging the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest. But God, being rich in mercy, because of His great love with which He loved us, even when we were dead in our transgressions, made us alive together with Christ (by grace you have been saved), and raised us up with Him, and seated us with Him in the heavenly places in Christ Jesus, so that in the ages to come He might show the surpassing riches of His grace in kindness toward us in Christ Jesus. For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, so that no one may boast. For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them.
For Paul, the phrase "in Christ" carries a special meaning. In that phrase he indicates those in whom God is at work and due to this, they walk "in Christ", no longer walking according to the course of this world. When Paul says that those "in Christ" shall be made alive, the promise is specific and unique to his followers, not all of humanity.