The key here is moderation. You don’t need to jam such arcs into every superhero movie—and if you do have to have one, you don’t always benefit from spending long stretches of time on it. There are so many other interesting things you can do in a superhero narrative, and Civil War gives itself the space to do a lot of them. Being that there are two significant character introductions in the movie, it was safe to assume that we’d have to see some manner of establishing backstory—and while there is for each hero a smidge of explanation, there’s nothing like a full who-they-are-and-how-they-came-to-be spiel.