When "Firefy" first appeared on TV in 2002 I missed it completely. I had to buy the series on DVD. Some of the themes in it really struck me.
What impressed me most can be summed up in what Mal Reynolds said about his ship (significantly named "Serenity"): "This boat is my home."
Many of the episodes can be summed up in that comment, because the main themes in the series are about freedom, home, and community. Which is something everyone wants, except the natural-slave types.
The crew members are a family, and they eat communal dinners together. Just as a family is supposed to do. When Jayne Cobb tries to betray the family Mal tosses him in an airlock, intent on dumping him in space, but when Jayne begs, "Don't tell them what I did" (meaning he's concerned, even on the point of death, what the family thinks of him) Mal relents and lets him live.
The cultures on the planets (some cultures, at least) are portrayed as true communities. In one episode River Tamm encounters some people doing an Irish jig and delightedly joins in (why is it every time I see the most fun dancing in a movie they are always doing an Irish jig? - see Soldier and Titanic).
It is significant that River is crazy, because the State fucked up her brain to make her a bioweapon, and at the end of the series she becomes whole, in large part because the members of the ship accepted her into their family.
River is the most intelligent, sensitive and intuitive person on the ship - and she is the one the Alliance went out of its way to destroy.
Joss Whedon said the series was based on Michael Shaara's novel about the Battle of Gettysburg, The Killer Angels, which was the turning point in the War Between the States (if only Joshua Lawrence Chamberlain had realized he was on the wrong, Union side).
For that matter, the bounty hunter in "Firefly" is named Jubal Early.
The Alliance is supposed to represent the North and the Browncoats, the South.
Here's where things get interesting concerning a theme I see all the time: the Machine State versus the Natural State.
The Alliance represents the Machine State and the Browncoats the Natural State. The Alliance is mostly military and everyone dresses the same, since they are cogs in a machine. They aren't free, no more than the stormtroopers in Star Wars are free.
There is little portrayal of any home, family or community in the Alliance, just fear of the meddling State. Mal, a smuggler who bought his ship to escape from the Alliance, kills its agents without a second thought.
Mal is actually a patriarch/protector, and his crew is his family. He is brave, resourceful, and confident.
You can see the same Machine State/Natural State theme in Star Wars, in which Darth Vader, who is half-man/half machine (Joseph Campbell called him "a bureaucrat") represents the Machine State (as does the entire Empire) while the Ewoks represent the Natural State. You can also see it in H.G. Wells' The Time Machine in which the Morlocks represent the Machine State and the Eloi the Natural State.
What the series is telling us is that the purpose of the State is to turn you into a machine and take away your freedom, your home, your community - in fact, to turn you into a replaceable cog in a machine. It means to take away the meaning and importance in your life and replace with allegiance to the State (which the deluded call "patriotism").
Your meaning and purpose becomes what the State says it is - mostly die in wars (see the aforementioned Soldier, with Kurt Russell).
You can apply the Machine State/Natural State theme to everything. Public schools? Cosmodemonic Transnational Megacorporations? Do I really have to explain?
What I will explain is that the State is about fear and slavery, and as Roy Batty told Rick Deckard in Blade Runner, "Quite an experience to live in fear, isn't it? That's what it means to be a slave."
"The family is fundamental; religious affiliation, ethic solidarity and other associations provide emotional support, meaning and interaction/relationship building based on shared experiences and values." - DayKoons