I have a couple of current cartoons that I keep on a mental list to show my hypothetical future children someday, if I don’t like their contemporaneous television offerings. Steven Universe is on that list for a lot of reasons. Here’s one of them.
Something that Steven Universe does very well is develop its characters through the eyes of a developing character. The series is told almost exclusively through Steven's point of view. There are some flashback sequences that show events Steven was not around for, but they are always presented with the framing device of someone telling Steven the story. We, the audience, learn about the world at the same rate as Steven. As such, we can only know what he knows, and can only see the people around him as he sees them.
But Steven is not a static character, so the way he sees the people around him changes. At the beginning of the series, Steven is very childish, with a black-and-white view of the world. He sees the Crystal Gems, his parental figures, as one-dimensional, uncomplicated superheroes - and so that's how they're presented in the show for us to see. We see Garnet as a flawlessly competent, all-knowing leader; Pearl as an amusingly neurotic, above-it-all mother figure; and Amethyst as a carefree goof-off. In the town of Beach City, we see one-dimensional goofy fathers, teenage slackers, and conceited politicians.
As the series continues, and Steven goes on adventures and grows up a bit, he starts to see the people around him more complexly. Through Steven, we witness candid moments in which the Gems reveal themselves as multi-dimensional people. And best of all, once we've seen that, the show doesn't go back. Though the first few episodes are pretty formulaic (there's a monster to fight, and Steven learns about a new Gem power), the show very quickly establishes itself as anything but a story where the status quo is restored at the end of every episode. Steven remembers what he learns. Once we realize that Garnet doesn't actually know everything, or that Pearl is still grieving the loss of Steven's mother Rose, or that Amethyst has guilt over the way she was born, or that absolutely no adult figure in the story really knows how to raise a magical child - we don't forget it, and that information colors the rest of the show.
So we see the Gems and the people of Beach City struggle, and learn from their mistakes, and grow and change as people, to the point where in a recent episode a character comments, "Nothing is like it used to be. My old life, my old town... they've all changed."
And this change is presented as a good thing. Not an easy thing, certainly, but a good, natural thing. We see Steven navigate a changing world, sometimes with frustration, but always with ever-increasing empathy and compassion. And through this story, we reflect on our own world, which is just like Steven's (minus the alien invasions).
There's a moment, or several moments, when an authority figure in your life (like a parent, or a teacher) suddenly appears to you not as a powerful, all-knowing being, but as a person. It's the moment where it clicks that everyone has struggles, and everyone is trying their best. Steven Universe shows its titular character have that moment again and again, often repeatedly in regards to the same person, as his view of the world expands. Along with Steven, we walk through the surprise we feel at that moment, and through the anxiety that follows as what we thought was rock-solid in the world turns out not to be, and ultimately to the acceptance of a world in which everyone is a whole person who is trying their best.
Ideally, going on this journey with Steven helps us to see our own world more complexly as a result.