This is really interesting. Part of me is doubtful, thinking perhaps everything we have is, however creative, some manipulated derivative of the known world. But then part of me wonders if we may very well have anyway, no matter a living example.
Dragons help me to articulate the half of me that thinks we may well have anyway—these fantastic beasts that breathe fire—the dragon-lore is based on fossils of dinosaurs (very much inanimate and undemonstrative,) and there is no other creature we have ever observed that does anything close to breathing fire (at least I don’t think there is…). Even if it was inspired abstractly by something—the heat on our own breaths, or some visual trick of a leaping flame at night that looked like a puff of breath—it required some more obvious novelty on our part, I think? So maybe we would have been able to imagine flight from some similarly abstract inspiration. But it’s hard for me to think of a world in which humans don’t imagine flying, so I think I’m leaning in that direction.
At the very least, I imagine issues regarding falling would have lead to some form of parachute, and with it a growing understanding of aerodynamics—so, perhaps, to the idea of steering the fall—and then, perhaps, to trying to lengthen the fall or keep a person airborne? Not sure, but seems like that could potentially be a natural progression with or without examples of flight surrounding us.
Of course, if we live in a world where there are not flying life forms, I would wonder if that has something to do with the difficulty of flight on that world (our world has an abundance of flying life forms!)—in which case, it might be much harder.