Not that I was born then, but from what I can tell they were originally written and marketed as fantasy, with teh sci fi elements coming later in a sort of creation-myth origin story.
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I know what you're trying to say, but McCaffrey always considered them to be science fiction, and the first edition of Dragonflight had a prologue that explained the existence of Pern as a colony world.
And I wasn't aware that an epic fantasy required the person who saves the world to be superhuman or anything. In fact, the general formula for epic fantasy is that a farmer's son or street urchin or some such person gets dragged into something larger than himself and ends up saving the world. He or she may discover he or she has some special ability or power (and may even be the secret heir to the throne or something) but is ordinary in most respects, even flawed.
And in LoTR, Frodo was a normal guy who was doing the best he could. He didn't have any special powers or anything aside from courage and a sense of honor. But he got the ring thrust off on him by his uncle and had to see things through to the end, even though it nearly destroyed him. He wasn't even a chosen one, really, except that he inherited the ring from Bilbo. So is LoTR not epic fantasy because Frodo lacked special powers and because he was "chosen" more by happenstance than divine providence or something?
In Dragonflight, Lessa started out living a life in hiding (the last of a noble house), and she was chosen by her world's last queen dragon (who knew, subconsciously at least, that she needed a special rider). Lessa had a special and unusual ability (talking to dragons that weren't hers ... though that became more common in later Pern stories). She gave up her inheritance (Ruatha) to do the right thing, and she saved her world in book one by taking a terrible risk and almost dying. Then in later books, her leadership and ingenuity continued to be a factor (though she had plenty of faults).
The Pern stories never had an out and out war, except for FAx's depredations at the beginning of DF. Once thread started falling, war became untenable (though the dragons came close to fighting at one point). But the world was still threatened by something larger than everyone.
I still say that sounds pretty epic to me, fantasy or no. More so, even, than LoTR when you compare Lessa to Frodo.