The MCU is one of the greatest movie sagas of all time. It is as entertaining as it is thoughtful and set such a high bar for quality that no one has yet to match it (not for lack of trying). Characters who were once second-tier, like Iron Man, have become super popular household names, found on everything from t-shirts to tattoos. However, of all the celebrated heroes in the Avengers, only Captain America can be considered a legitimate honest to goodness hero. Though they performed heroic acts and frequently put their lives in danger to save the world, only Captain America deserves the title for its truest sake.
Captain America: The First Avenger was the fifth movie in Marvel’s Phase One, the last entry before the first Avengers hit theaters. Steve Rogers (played by Chris Evans) is a skinny hapless do-gooder recruited by Dr. Abraham Erskine (Stanley Tucci) to be the test trial for a super-soldier serum originally developed in Nazi Germany. The transformation of Steve Rogers is successful, but Dr. Erskine is tragically assassinated, and the remaining serum destroyed. As Captain America, Steve fights in the Second World War against the original serum test subject, evil Hydra boss the Red Skull. Captain America thwarts Red Skull’s nefarious plan and sacrifices himself to save the east coast of America by crashing a bomber into the frozen Arctic Ocean. Seventy years later, Captain America is thawed and brought into the modern world.
Out of all the MCU heroes, only Captain America chose to be a hero. More than that, he did so before he even gained superpowers. The first thirty minutes of The First Avenger proves the true character of Steve Rogers. Despite his list of health issues, he countlessly tried to join the army to fight overseas. He believed in the cause of fighting fascism and felt guilty when he could not do his part. Rightly so, Steve is rejected for recruitment by the officers until Dr. Erskine sees that one special trait in him: selflessness.
During training at Camp Lehigh, Steve shows his selflessness by diving onto a frag grenade to save his fellow troops, one of which was a bully. The grenade was a dummy, but the act clearly demonstrated his true heroism. Steve Rogers was a hero well before he became Captain America. That the serum amplifies the host’s inner characteristics is telling in all the ways Steve goes on to save the world in future movies, and how he stands his ground even against his best friend when the world goes down a dangerous path in Civil War.
Further evidence is how Captain America can freely wield Mjolnir, both in Age of Ultron and Endgame. In Age of Ultron, Steve Rogers attempted to lift the hammer only to move it a millimeter before giving up. Truly, like fans see in Endgame, he could have lifted it at any time, but being the good friend that he is, he chose not to challenge Thor’s big hammer energy. Vision did it to prove his purity and gain the Avengers' trust. They questioned whether he was in league with Ultron or not, and so it was an act of good faith.
Steve Rogers was a hero internally, not externally like all the others. If Tony Stark skipped his trip to Afghanistan in the first Iron Man, he would never have been attacked by the Ten Rings and wounded with shrapnel in his heart. He would still be a rich playboy selling vicious weapons to the highest bidder. Both Thor and Black Panther inherited their powers and titles from their parents, they are a matter of birthright. Hulk, Spider-Man, Captain Marvel and Doctor Strange were accidents, where much like Tony Stark, an external factor derailed their normal course of life. Ant-Man, Black Widow and Hawkeye are employees; the Maximoff twins and Vision are creations. If the inciting incident missed any one of them, they would not be an Avenger, nor would they put their lives in harm’s way.
If Steve Rogers did not get the serum, he would never have fought in the Second World War. He would, however, still get into fist fights with jerks in back alleys. He would still stand up for what is right, not what is convenient. He would still uphold a moral dignity, a true virtue and be the paragon of those values to the next generation. Captain America: The First Avenger proved it by showing how Steve Rogers was as much a hero before the serum as he was as Captain America. In fact, compared to the others, he is the only real hero in all the assembled Avengers.
MCU fans all have their favorite hero. Some, like Spider-Man, are more popular than Captain America. Each character contributes their own awesome personality and heroism to the tapestry at large. In the end, so long as the Marvel Cinematic Universe keeps making high quality movies, the fans always win. That is what it has always been about.