Interesting OP. But there is a far deeper problem with the ransom issue. Adam did not introduce sin into the world. Eve did! But the NT falsely attributes the introduction of sin among the human family, to Adam. Why do you think that is?
Romans 5:14; 1 Corinthians 15:45-49 both convey the idea that Christ is similar to Adam and 1 Timothy 2:6 can mean "corresponding ransom" given that the prefix anti in antilutron has "corresponding" as one of its meanings. Admittedly it also has "exchange" and "instead of" as meanings and these latter meanings also fit the context of the verse. So I wouldn't be so quick to knock Watchtower's premise that the ransom had to correspond with Adam.
In fact, I think it explains why the NT falsely blames Adam for the introduction of sin into the world instead of more accurately blaming Eve as being the first one to sin and who got Adam to sin. You see, if the NT blames Eve for introducing sin, then that would mean the ransomer who had to die would have to be a woman like Eve was. But the patriarchal misogynistic society in which christianity was born, could not stomach the thought of a woman having such a prominent role. So to solve the issue, they just ignored the fact that it was actually Eve who sinned first, and pinned the introduction of sin on her male accomplice, Adam.
Another possibility is this: The sacrificial messiah that christians thought up in Jesus, is not really the messiah foretold in the OT. The Jews' conception of the messiah is actually the "correct" one - i.e. the one intended by the OT writers - while the christians' conception of the messiah being Jesus, is actually fraudulent. Jesus is just another one of a long line of fraudulent messiahs that popped up around the first century, but with one distinction - he happened to be more successful in inspiring his followers so that he left a surviving legacy behind. That would explain why some of the OT texts that are quoted in the NT as prophecies of christ seem so mundane and unprophetic in their original OT context. The early christians were basically taking random OT quotes that had any vague similarity to Jesus' circumstances and styling them as a prophecy in a post hoc manner.
That would also explain why Adam has to be dishonestly shoe-horned into the salvation-ransom narrative as being the introducer of sin. Jesus was a man and so as a sacrificial offering he had to correspond to Adam and not Eve. But that Eve introduced sin into the world is without dispute when you read Genesis. In fact, it is even apparent that one of the objectives of Genesis 3 is to provide an explanation for why women are subjugated by men, treated as property, and more sinful - because of Eve's sin. Eve sinned first so as punishment women occupy a secondary, servile role in human society - that is one of the messages implied by God's words to Eve when confronting them on their sin.