Since Avengers: Endgame's release, Marvel Cinematic Universe fans have come up with numerous reasons why Steve Rogers couldn't wield Mjolnir in Avengers: Age Of Ultron. Some believe the secrets that Steve kept from Tony Stark -- that Bucky Barnes was responsible for his parents' death -- prevented him from being worthy. According to directors Joe and Anthony Russo, that is far from the case: Captain America was always worthy.
"I'm sure it was probably in Kevin's mind well before [Ultron], which is why he probably asked Joss [Whedon] to include something like that. At some point he wanted to see Cap worthy,” Joe Russo told Empire. "But it's one of those things that you can only pay off with 10 years of storytelling behind it. To know everything that Cap has gone through, and to see who he is as a character and all the choices that he's made, he is worthy. Even though he's made mistakes, which is I think fascinating -- even in Civil War when he admits to Tony that he withheld the truth from him, it doesn't alter the fact that he's worthy.”
Much like Thor -- who remained worthy of wielding Mjolnir throughout Avengers: Endgame, despite failing to save Asgard and its people and then losing the battle to save half of the universe from Thanos -- Cap is worthy because of and throughout his failings. It seems the MCU is sending a strong message about flawed heroes. By continuing to fight for what’s right, despite flaws and failures, essentially any hero can be(come) worthy.
Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as Bruce Banner, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Brie Larson as Captain Marvel, Paul Rudd as Ant-Man, Don Cheadle as War Machine, Karen Gillan as Nebula, Danai Gurira as Okoye and Bradley Cooper as Rocket, with Gwyneth Paltrow Pepper Potts, Jon Favreau as Happy Hogan, Benedict Wong as Wong, Tessa Thompson as Valkyrie and Josh Brolin as Thanos. The film is in theaters now.