If there had been no flying animals, would the airplane have ever been invented? To even attempt flight, we had to believe it was possible. We had to see birds and dragonflies to get the concept.
Nobody today dreams of gliding through rock. Why not? What if there were animals in nature that could swim through a granite mountain and come out the other side? Assuredly, we would want to be able to do that too.
Would we have gotten the idea of flight from a maple helicopter or a dandelion parachute? We might have thought about gliding or floating downward, as seeds do, but never about hot air balloons or the Bernoulli effect. The Bernoulli effect might have been discovered anyway, but it would not have been applied to the problem of achieving human flight, because that would not even be a consideration. If there are no animals moving about in the sky, why would you even consider flying?
Anthropomorphism is the key. We have a certain physical empathy with the exertions of other animals and that is what prompted us to think, if they can do it, why can’t we?
What about flying squirrels or even leaping lemurs? Again, maybe we would have gotten the idea of gliding downward, but not flight. We have the birds to thank for Boeing, Airbus, and even NASA