Is it? Iron Man has long been an Avenger, but he was hardly the top-flight, everyone-loves-him character that he became because of Mr. Downey's performance. As a film, Iron Man definitely does do some of this thing, and it's a pattern you see in plenty of other entertainment spaces. Remember when we had the era of (alleged) "WoW-killer" MMOs? Not a single one of them succeeded. The thing that finally took WoW down a peg, that finally got people into another game...was WoW itself failing to deliver. From what I've heard, they've turned the ship around and the fans are largely hopeful again (I made my peace with WoW long ago), but it's going to take more than two successful expansions to win back the goodwill they lost.
Or consider Watchmen. Not the film--the "graphic novel". Watchmen is a good story (albeit not for the reasons many of its fanchildren love it!), but it and a couple of other similar comic stories from around that time (such as God Loves, Man Kills) almost directly inspired the so-called "Dark Age" of comics, where everyone had grim and gritty reboots and all the new heroes had edgier-than-thou sobriquets like Deathbloom or Bloodnyte or whatever with kriaytyve spellyng and outfits that showed lots of T&A and used guns and knives and probably did drugs etc., etc., etc.
It's not a strawman to say that it's quite common to see a popular and well-made thing that worked, and then a whole passel of imitators came along, trying to distill out only the secret sauce without really understanding or putting in the necessary effort. It's no guarantee, but it certainly isn't uncommon either. Further, many sequels suffer tremendously from what various groups (I first encountered it in music) call "sophomore syndrome/slump", where a first attempt does incredibly well and a second attempt...doesn't. Consider the different responses to Avatar: the Last Airbender and Avatar: the Legend of Korra. LoK was actually okay, though it made a number of stumbles and not all of them can be blamed on executive meddling. (Seriously, deleting Korra's past-life connections--literally forcing a shattering of spiritual traditions, a forgetting of one's past and where one came from, in order to integrate into modern society!!--was....not a good look and not well-handled. To say nothing of its piss-poor handling of spirits...but I digress.)
Point being: True sequels are hard. Merely following the outline of a previous successful work is even harder, and often fails...but people keep trying anyway.
I....think you are misunderstanding. There wasn't one. Raimi (not "Ramey") directed the first Spider-Man film in over 20 years. And, like Iron Man, it got two sequels and then petered out (no pun intended.)
Oh, believe me, I'm quite well aware. It's usually my generation they're trying to pander to with these things. I call it "Instant Nostalgia"; we're getting "live-action remakes" of animated films that, in some cases, aren't even a decade old. And for most of them, the fact that it's live-action is literally the only thing going for them.
I mean...I don't think that's that far off-base? There's a reasonable thesis there. Whether it was well-defended is a different question, but "taking a somewhat obscure character and making a good film about them" has some teeth to it. I'd want to more carefully analyze the sample set, to be sure, but...well, I mean, I used ATLA and TLK for a reason, ATLA definitely was a risky and fairly experimental concept but it is still beloved and cited frequently, while TLK (for a variety of reasons, as noted above) is...not as well-received.