The hype and popularity of Iron Man, is just because of its amazing characters.
Tony Stark has been into a role that has made him go against all the odds. He has been the combatant for the entire Saga of Infinity. In the total number of films in the whole Marvel Cinematic Universe, Tony Stark has been the most unusual and outstanding character. Stark had worked tremendously to stay in the lead, and for that position, he is worthy enough because of his extraordinary heroic skills. And because of this, Tony is better known to be the Iron Man.
The Introduction of Tony Stark as Iron Man

When the viewers got to know Tony Stark initially, they didn’t spot him as the protagonist. Instagram of that they thought him to be a bossy, egoistic, and rude billionaire who was not even ready to accept an award at a place where he already gambles. After his journey to Afghanistan, he gets the cost of how his family and his way of living have snatched from innocent beings. For the first time, with this, Tony gets aware of the heaviness of the Stark name. After the loss of Yinsen, his family gets to see how Tony beat down the bad image of their industry as Obadiah Stane. Hence, from thereafter he states him as the ‘Iron Man’.
The Legacy of Stark – Iron Man (2)

In this part, the audience gets to see a different phase of Stark. He gets distressed about the Stark legacy. The way he handover his company to Pepper and an Iron Man suit to Rhodey, the way he giveaway to the Boy Scouts his arts, these all make us see the way how everything gets implemented. With this, the safety of Tony from his fate, and the coming up of negative characters have been all responsible because of the Stark Legacy.
Ego (Avengers)

Going into Avengers, Tony is feeling awfully confident. He’s learned from his past, overcome death multiple times, and he’s two for two versus the only real threats he’s met since becoming Iron Man. Tony has learned that he doesn’t have to do everything alone, but that doesn't mean he’ll work with anyone he doesn’t trust.
This is where both the main friction and the most growth comes for Tony in Avengers. He is forced to acknowledge that he may not always have the answer. If coming into contact with people like Thor and Cap weren’t enough of a shock to the system, delivering a nuke through a wormhole and narrowly, luckily surviving will have some lasting effects.
Overcoming Trauma & The Man In The Suit (Iron Man 3)

By the time we see Tony in Iron Man 3, it is pretty clear that he’s experiencing PTSD. He can barely stand to be in public. He’s having panic attacks. He can’t sleep. Tony just isn’t acting like the man he used to see himself as. Stark has finally been served his slice of humble pie and it’s much larger than he could’ve ever anticipated. He’s flown right into the void, and somehow, through pure coincidence, he’s managed to escape with his life and return to the world.
The Curse Of Knowledge (Avengers: Age Of Ultron)

During the events of Avengers: Age Of Ultron, we see the culmination of everything that has been weighing on Tony’s mind since the Battle of New York. The good, and, unfortunately for Tony and the world as a whole, the bad. Tony creates Ultron as a direct result of his fears and paranoia, and ultimately, it costs him and many others.
Growth & Accountability (Captain America: Civil War)

A lot has changed for Tony in the years since he announced to the world that he is, in fact, Iron Man. For instance, when the Sokovia accords are pushed on the Avengers, Tony accepts that they shouldn’t be allowed free reign to solve the problems of the world. This essentially puts himself into the exact indentured servitude he fought against in Iron Man 2. We also see that Tony has gone out of his way to seek and advise the young Peter Parker.
Fatherhood: Tony’s Legacy (Spider-Man: Homecoming)

Through programs like Damage Control, fans see Tony build on his commitment to accountability. Meanwhile, through Tony’s relationship with Peter, fans begin to see Tony dabble in the waters of fatherhood. While Howard was cold and distant as a father, Tony begins to display how loving and involved he can be. He knows who he is, without question, and he knows that Peter can be better if he’d just listen to Iron Papa.
Fatherhood Part 2: Sins Of The Fathers (Avengers: Infinity War)

It’s no mistake that both Tony and Thanos lose their children in this fight. It’s also certainly not a coincidence that Peter’s dusting is both the longest and most gut-wrenching. Tony may have secured the Stark legacy with Pepper in charge of Stark Industries, but he's just watched his legacy turn to dust before his eyes.
Fatherhood Part 3: We Are Who We've Left Behind (Avengers: Endgame)

Well, here it is. The end so many, including Tony himself, have been fighting against for so long. The death of Iron Man. With three simple words, Tony saves the lives of everyone in the MCU. Tony, like many great fathers, leaves his children prepared to take on whatever the world may have in store for them. He’s given Peter an unattainable goal: Be better than I was. He’s seemingly given Harley the same responsibility. To Morgan, he leaves behind the memory of a powerful father truly devoted to his children. And to the MCU as a whole, Tony gave something much more powerful. A new beginning.