Men (at least some of them) have the natural gift of their brains, which leads to the capability of constructing machines able to carry men through the air, over the ground, and across the ocean (and into outer space). The lion has teeth; the bear has enormous strength; man has a brain.
But it still stands that man does not fly; the machines do. Man is simply along for the ride. (Unless you count Superman.)
While your point is well-taken, I'd like to point out here that there are many well-attested and historically-verifiable instances of humans "flying" without benefit of airplanes, balloons, or other devices. I speak, of course, of God's saints, many of whom were able to fly (the technical term is "levitate") through the miraculous power of God. St. Joseph of Cupertino, patron of airmen and astronauts, was seen flying through the air by dozens of people on many difference occasions. With God all things are possible.