Team Stark was all about keeping superhumans (and normies with supertech) accountable by yoking them to some government body. Team Cap was about how that was a bad idea.
What neither side addresses is that the question is fucking pointless. Proper superhumans are demigods, and demigods are a law unto themselves. Normies can't do jack shit about them, and the demigods know it. You want to know what would happen if we got superhumans? Doctor Doom, Black Adam, The Authority, The Justice Lords, and the god pantheons of mythology are what you will get.
Normies forget that what they think is real power isn't. It's an illusion. It requires that other normies go along with what you want, and once folks remember that their "power" goes POOF! and reality sets in: you're just some guy in a world with just some guys, and you can only do so much on your own.
Superhumans have real power. Power that can't be ripped from them by normies, that doesn't require another's support of them, and therefore can only be dealt with as one does a dangerous animal: killing them or avoiding them. Since normies are unlikely to be able to kill a demigod, avoiding becomes the way to go, and that makes a mockery of normie perceptions regarding their place in the universe.
And this is not idle conjecture. Governments have been after so-called "super-soldiers" since Captain America first hit the stands, at the very least, in the stupid hope of creating a leashable demigod to yoke to government service. While creating supertech isn't quite so dumb, as tools can be alienated from "rogue" users, it's amounts to the same thing in practice.
So, if you want to know what "transhumanism" will produce if it succeeds, you know where to start: mythology. The gods of the pagan world are utter pricks for a reason, and that's because they know only their own can check them. So it will be if we fuck up and make demigods ourselves.