Speaking of inspirations...
It seems likely that the "Flash Gordon" comic books and serial were inspired by ERB's writings, notably the "Barsoom" and "Venus" series.
"Star Wars" was most definitely inspired by "Flash Gordon". In fact, George Lucas apparently wanted to make a "Flash Gordon" film, but couldn't get the rights to do so, so made "Star Wars" instead. (And, incidentally, the same is true of "Willow" and "Lord of the Rings". Now, wouldn't that have been interesting...?)
After "Star Wars", there was a flood of other sci-fi produced, including "Battlestar Galactica" (the original), the "Flash Gordon" movie, "Buck Rodgers in the 25th Century" (the TV series - the original stories predate SW of course), and so on. Plus, of course, the "Star Trek" movies, "Next Generation", and the rest.
Then there's "Babylon 5", which is clearly sci-fi, and clearly inspired by SW, ST, and others, but is also inspired by fantasy writings, including "Lord of the Rings", Elric, and probably the Cthulhu mythos. Oh, and the King Arthur legends.
The key effect of B5 was to change the way TV shows told stories. Suddenly, you didn't just get a bunch of standalone episodes; shows had to have an ongoing plot. "Buffy" refined this concept, switching to a season-long plotline (as opposed to B5's five year epic), which spawned "24" and other shows.
But, importantly, B5 also gave rise to the new "Battlestar Galactica" and also to "Lost", neither of which could have done anything of the same scope had not someone showed the way - and both have distinct stories with a beginning, middle and end (even if "Lost" gets, well, lost about halfway through, and neither show ends very well).
Meanwhile, we get the "Star Wars" prequels, which build on much that has gone before. Those get mixed receptions, but do better than the last few "Star Trek" movies, which kill that series. But that, in turn, works out quite well, because we then get a reboot of the ST movies, which sensibly go for a much more action-movie vibe to them. By embracing that aspect of the series, they don't make the mistake of trying to be something they're not - much of the success of ST:TNG is due to Patrick Stewart in the lead role, but while he's a great actor, an action hero he is not.
And now we get back to "John Carter", which is adapted from those original stories (of course), but which features scenes that look very much like they were just lifted directly from "Star Wars" (and, actually, "Lord of the Rings" in at least one place).
There isn't actually a point to this post, you understand. (Maybe I should have said that at the outset.) I'm just intrigued at the way everything is now feeding off of everything else in a big symbiant circle. Plus, now I'm wondering what's next in the chain.