Steven Universe was made by a women named Rebecca Sugar, who also worked Adventure Time (she no longer works on it.) That's why you can probably see similarities to the shows. She's really famous for making really good songs for both shows. Especially for Adventure Time. Although she doesn't work on Adventure Time plot wise anymore, she is invited all the time to making songs for it.
The show revolves around "gems" who are asexual beings. The whole show is mostly taken place in a city called "Beach City" which has a ton of references, just like the show in general. As put by the creator, the gems you see (aside from Steven) are mere projections of the gem in human-esk form. They don't have a gender, really, but they do have pronouns in which they identify with. All of which (as of right now) identify as female. Gems didn't come from Earth, either. They are all from "Homeworld." Rose and the gems (however they met) love Earth and have been protecting it for thousands of years. Steven is a boy, who's mother was a gem (Rose Quartz) and his father was a human. Thus when he was born, he is half human, half gem. Gems cannot, essentially, normally give birth. His mother had to give up her physical form to create Steven (there's really no part in the show that goes more into detail, but I'm sure Sugar will provide it sooner-or-later.)
During the show the gems really have to deal with the loss of their leader (Rose Quartz) and have to take care of Steven. They don't really know how to take care of him since he is a child and they raised him when he was very little. They come face-to-face with a lot of difficult subjects and other gems that attempt to exploit earth.
The show is actually really mature, especially for being on Cartoon Network. Most of the stuff on there is just barely passable by CN, but like Sugar had said "They let us do anything with the show as long as we can explain why it's important." Most of the stuff can really tug at your emotions because that's exactly what Sugar wants. She and Ian actively try to make the show emotional and loving towards everybody of all ages and genders and that's exactly why the show is amazing to me. Steven Universe brings a lot of things together you wouldn't normally see. The show isn't just a "cater to Tumblr." It's a lot more. The explanation above is just my mere wording. If you want a more reasonable plot explanation, then google it.
I really do love the show. It's tugged at me a lot. Especially the last "Steven Bomb." If you only watch the first few episodes, you're not going to get the full experience, though I do understand if you don't like it then. The beginning is slow to most people, but later it's a lot better and the art does improve greatly in the middle of the show.
Edited by Wundy, 22 July 2015 - 01:42 PM.