Remember when there wasn't an MCU? The medieval times of a decade prior, when Marvel was mostly just a comic book company?
Think back on that landscape and try to recall how many people actually knew the names Tony Stark, Iron Man, or Avengers. We don't have a headcount, but it was way fewer than it is today. Then Robert Downey Jr., Kevin Feige, Jon Favreau, and company got together to put Iron Man on the big screen, and after its premiere 10 years ago, the geek world was never the same.
Part of the reason the film (and the MCU) launched so spectacularly was the way it drew non-comic book fans in right off the bat, with an Oscar-caliber actor doing realistic things that don't feel too sci-fi: testing weapons, getting kidnapped by terrorists, and, like a blacksmith of yore, building a weaponized suit, which he uses to escape a very intense hostage situation. Not all that relatable, but at least believable.
Indeed, the far-from-polished Mark I, as it would come to be known, was created out of necessity, a rust bucket forged by desperation and ingenuity, with a little help and plenty of sacrifice from Dr. Ho Yinsen. Using nothing but raw parts, the building process puts to shame anything McGyver ever invented. The man whose math is always right builds a prototypical Arc Reactor, then uses it to power a giant iron suit, replete with a Manually Deployed Rocket Launcher, flamethrower arms, and Jet Boots.
Granted, the crude suit had nothing on the many Marks that came later. It couldn’t fit in a suitcase; it couldn’t meet up with Tony half way around the world; heck, it couldn’t even Hulk-bust. But what it could do was create a superhero right before our very eyes. And for non-comic book fans, that was kind of a big deal.
After 10 years, Marvel has done a heck of a job informing folks about their heroes, to the point where they don’t even need to include backstory or character development anymore. Marvel expects us to know the Avengers at this point. And we do, judging by all the people who have seen Infinity War so far. But unless you were reading comic books back in 2008, you probably didn’t have that much of a clue as to who Tony Stark was.
So for Iron Man to appeal to a mainstream audience, they had to develop the character, and his powers, realistically. Or at least enough to establish the reality bar. Which is exactly what the film did, by setting up Tony’s predicament — getting kidnapped by terrorists with a legitimate agenda, imprisoned with a fellow scientist, forced to use their genius to make a weapon for said terrorists, and then using their wits to turn that weapon against them.
And so we have plenty of reason to love the Mark I, even if we won't see it taken out of the shed any time soon to take on Thanos.