Firefly to me is more of a show about humans in the future than scifi. There are no aliens in the program, somthing I like alot, because I don't believe there are any intelligent aliens out there within reaching distance. It's just about humans that have colonized space when the earth was used up.
And about the political and social problems that will develop along with that colonization. I think it's perhaps the most realistic estimation of what our future in space may be like of all the space tv shows over the years.
And, just like when North America was settled, weapons will play a big role in remote areas of space where civilization or laws are sparse.
I also think the program has meaning for individualists more than collectivists.