Remember, Ellie is a leader. It’s something we’re told more than shown, until we look at her in comparison to Joel. The child leads the man.
Here’s an interesting thought: is Ellie an Eight? Usually I wouldn’t like two main characters sharing the same Enneagram number, but this might work. Ellie displays the positive traits of an Eight. Leadership, bravery, loyalty, and an awareness of how her actions impact greater society. Joel is the negative. He’s brave and loyal, but not in the same way. He’s the guy the mob boss can depend on to do the dirty work. Ellie and Joel are both the kind of people you need in a dystopia, but Ellie’s the one you want to keep around after society begins to rebuild. Joel’s the one you want following Ellie’s orders.