While Joss Whedon was already a house-hold name (sort of) with Buffy and Angel, he became the god all the geeks pray to only after Firefly debuted. It was a bold move proposing such a concept, even if it must have been forced (as the writer/director said, he was supposed to come up with a new idea and this was all that he had left).
And it was bold indeed, since the new series was supposed to be a sci-fi movie with western accents, something which had little to no chances of capturing the audiences. He knew this but still believed in his vision – he didn’t want to emulate any other writer or director, just like he didn’t want to create a series which had too many commonplaces with other sci-fi productions.
So Joss Whedon drew inspiration for this series from Stagecoach, a 1939 western starring John Wayne. At the same time, he aimed at presenting the life on the frontier not from the perspective of those that make history, but from the point of view of those that history forgot.
Of course, since I am mentioning life on the frontier in space, the obvious reference in here is Gene Roddenberry’s Star Trek: Next Generation, with the famous line starting with, space, the final frontier.
But, in order to make Firefly truly original despite its sources of inspiration, Joss Whedon decided to go another way. He wasn’t afraid of looking a bit silly, just like he wasn’t afraid in the sequel Serenity to not come up with some huge threat that threatens entire existence.
In other words, the entire Firefly series (including Serenity) feels more organic than otherwise, given its distinct sources of inspiration. It isn’t the fact that the characters in themselves were written to perfection, but the fact that the quick strokes with which Joss Whedon sketched them left a bit of space for interpretation.
As a conclusion, I can say that a series (and even a movie, in the case of Serenity) shouldn’t take itself too seriously, just like it shouldn’t try too hard to up on a previous villain or event. If it feels alright, then it must be so.