Civil War is a perfect litmus test of how you are as a person. If you’re Team Iron Man, you’re an emotional, naive and impulsive person who cannot step back and look at the bigger picture. And ironically, that is exactly who Tony was.
Maturity is realising Steve was absolutely right. He understood what the Accords could eventually mean for the Avengers. He looked at the bigger picture. And that’s why every member of Team Iron Man who stood against Steve eventually realised he was right.
Tony realised he was wrong and came back to help Steve. Rhodey backed Steve against Ross in Infinity War. Black Panther realised he was fighting the wrong battle and helped Steve and Bucky. Natasha called out Tony and helped Steve. Vision also understood Steve’s position and called him for help in Infinity War.
Cap was right. And Mjolnir choosing him in Endgame was the perfect punctuation mark.