Anthony "Tony" Stark was born to Howard Anthony Stark and Maria Collins Carbonell Stark, owners of Stark Industries. As a child, he was fascinated with building and controlling machines (JARVIS and Dum-E). He entered MIT at the young age of 15 and graduated with two master's degrees at 19. At 21, Tony inherited Stark Enterprises when his parents were killed in a car "accident." However, he promoted his is secretary Pepper Potts, so he could avoid what he saw as a burden.
Unlike most heroes, Tony didn't need a super-serum, magic, or his parents to die. Iron Man begins where Tony Stark almost ends. During a field test for his military equipment, Tony and his party were attacked by a group of terrorists. The attack leads to a landmine going off and Tony being carried away with shrapnel deeply embedded in his chest, racing towards his heart.
At the camp, Tony shared a cell with famous physicist Professor Ho Yinsen. Knowing he would not survive with shrapnel in his chest, Tony proposed they combine their knowledge to build a battle suit, equipped with a magnetic field generator to prevent shrapnel from reaching his heart. The armor created was the first Iron Man suit and was equipped with limited weapons for defense. Ho Yinsen created a diversion while the suit charged and was shot to death, once charged Tony races into battle, a self-made hero.
What makes Iron Man so great? Well, it's because the man inside the suit is completely human. Tony Stark is just a man in a can, he has no real superpowers, only humanity. He has a huge amount of aspects that make him who he is, like how he values morals over finance. He didn't bat an eye at the drop in the stock market when he shut down weapons manufacturing.
Tony saw what his weapons were doing and shut it down. Not to mention his other great aspects, "Genius, billionaire, playboy, philanthropist." Out of a world filled with superpowered people, mutants, and skilled fighters, Tony has no powers and no fighting skills (other than hand-to-hand). Every superhero has a story about why they became who they are but for Iron Man, it's not the same. He is a genius in his own right and could easily make a difference with his brains and resources he goes a step further. He builds a suit of armor to fight beside the other supers because he holds himself accountable.
The man in the suit also has flaws. He suffers from paranoia and alcoholism. He also suffers from mental illnesses such as depression and anxiety. He is also suicidal. You can see these throughout "Iron Man 2" all the way to "Avengers: Infinity War". He physically cannot heal as fast as the other heroes. So he has to suffer from emotional and physical damage throughout everything he does.
Although the world has labeled Tony Stark as poisonous and egotistical about his past and flaws, he continues to show us why he's not. He knows that he is only a man in a can, recognizes that Steve Rogers is the boss of the Avengers, takes fault for Ultron, and recognizes that they have to work as a team.
His biggest show of humanity comes in two parts: "The Avengers" and "Captain America: Civil War." In the first "The Avengers" movie, Iron Man recognizes that the only way to redirect the nuclear bomb headed straight for New York is to fly it on someone's back. He is the hero to fly through a giant wormhole in space with the nuke, and in his last moments try's to call Pepper because he knew that he would most likely not return alive.
When Iron Man comes out of the wormhole, he comes back with the fear and knowledge that something bigger than the Chitauri is on it's way to Earth, hinting as to what will happen in "Avengers: Infinity War." Tony is so worried that he continuously upgrades new suits for him and his fellow Avengers and you can see this especially in "Iron Man 3." He uses his suits as a means to feel safe, the suits are his cocoon. He buries himself in them to deal with panic attacks and mental issues.
In "Captain America: Civil War," Iron Man and Captain America disagree on the Accords, and rightfully so, as both have their own reason and views on the matter. However, Iron Man agrees with the Accords because of his overall guilt that remains after "Avengers: Age of Ultron." Ultron was his fault along with Bruce Banner and Wanda, so naturally, he feels guilty about everything that happened. He believes that the Avengers should not solely decide on the course of action or if action needs to be taken at all. He believes that they should be held accountable for what they had done and the damages they caused.
Tony's decision to sign the Accords is even more heartfelt when it comes to the closest storyline to "Captain America: Civil War," you'll find in the comics. The Superhuman Registration Act was brought into effect when Nitro, a supervillain, detonated himself and killed children at a nearby elementary school.
Tony spearheaded the support for the Act, convincing Spider-Man to unmask as Peter Parker. The act required all supers to register their identities and subject themselves to federal standards. Captain America leads the resistance, and Tony Stark becomes Director of S.H.I.E.L.D. Not to mention that Tony watched his father glorify Steve Rogers his entire life, while being ignored, to only find out that Steve's best friend killed his parents, and Steve knew the entire time. That'd make even the best people a little angry.
Also, in "Avengers: Infinity War," Tony Stark jets off towards a flying spaceship because his teenage recruit and the wizard he just met were on it. When faced with the decision of returning home or going to Titan, the home planet of Thanos, he chooses Titan; he does this to lead Thanos away from Earth, so no more people have to die. He goes with Quill's plan of attack, along with Dr. Strange, to keep the time stone safe; and when Strange saves Tony's life in exchange for the stone, Tony would rather die. Tony would rather die than put the people of Earth in any more danger. He has shown us that again and again. (If you haven't seen "Avengers: Infinity War," it's been two months...)
Iron Man/Tony Stark is the best hero because he doesn't have any special power or strengths. Iron Man is more than a suit of armor; it's a metaphor for who Tony Stark is: cold and hard on the outside, but soft on the inside. This is a man who uses arrogance as a defense mechanism so people won't see how bad he feels on the inside.
Tony uses his suits to fix his mistakes. He's only human, what other superhero made the decision to fix a world they helped destroy, even though the world had already labeled them as egotistical. The child who grew up thinking he was a disappointment and spent his young adult life drinking and forgetting is now the first person to jump at the chance of saving the world. The suit saved his life and countless others with it. In Steve Rogers words, not mine, Iron Man really is "the worlds best defender."
