I’m not saying that the background features call for skill checks. I’m saying that the things they accomplish are typically accomplished by skill checks, not high level magic as you said, with whatever weird homebrew spell that you linked to.
These are not earth-shattering abilities we’re talking about. They’re ways for the PCs to interact with the setting. They’re not ways for people to win the D&D forever.
Well, except the PCs toss around fireballs, shrug off giant club hits from frost giants, and kill dragons.
But other than all that… yeah, same as a cobbler.
But who cares if it’s not part of the Iron Man film? If it doesn’t matter to the film, the n it doesn’t matter.