It flips the traditional parent/child/sibling family and friendship roles in society.
The deadbeat dad of Greg is one of the most reliable people there, and is only a deadbeat because a chilled out attitude was probably the best way of coping with shit in his life,and raising his son.
The 'more mature' mentor figure of Garnet is deconstructed as perhaps having the least conservative, or old fashioned roles in the group. Hell, the components of Garnet aren't chilled out, they're revolutionary in their attitudes in the context of the show still and extremely passionate for better or worse; however, this doesn't stop them fitting into the groove of their relationship, or basically having their equivalent of 'doing everything together, holding hands'.
Pearl is the dependable de facto mother figure, someone who is meant to work together with the father figure most easily. However, there's a lot of unspoken initial animosity between her and Greg initially, which is only alleviated by Steven. While this is usually cause by a percieved betrayal in real life, the real reason this animosity exists is the fact that in general, they're both standup people; their jealous or petty qualities mainly stem from their shared love of Steven and Rose, something that should be positive.
Amethyst is the elder sibling, and straight off the bat, she doesn't fit expectations. True, she entertains steven the best, and encourages him when he's having fun. More often than not though, Steven has to reassure Amethyst, or help Amethyst with being okay with her lack of context of HW, or falling short of expectations people have set for you.
Finally, we have Rose. She's the ever present subject, except she's never present. A martyr to a cause that puts steven in danger, yet someone who gave everything up for him; her paradoxical nature resembles that of many parents as they transition from child to adult.
I could do more, but character limit. Get the gist?