Actually, Hawkman’s boots, belt, and wings all contain the Nth metal, which allow him to use his mental abilities to get him off the ground.
I just watched The Death of “Superman Lives”: What happened?. Luckily it died.
It almost didn’t get made without Superman flying at all, then it didn’t get made with Superman jumping instead of flying under control which wouldn’t have been that bad except for everything else it didn’t get made with.
Superman flies exactly the way bricks don’t - Douglas Adams
The Earth knows that Superman sucks, so it only allows him to touch the ground when it wants to. It’s the whole “don’t tread on me” thing.
The Kevin Smith script had him flying, you just never saw it. It was just a red/blue blur.
A three-page thread about how Superman flies and no one has mentioned the thing every 10-year-old kid intuitively knows:
it’s his cape.
How does Superman fly?
He flies very well, thank you. Next question?
Oh, come on! The Earth weighs 6.6 septillion tons! How much could li’l ole Supe affect it by leaping just one tall building in a single bound?!? :dubious: 
:o
No, that actually makes sense. The immense acceleration needed for humanoid legs to bend and then stretch out, fast enough to propel a humanoid body the height of a (let’s say) 20-story building would, in fact, buckle any concrete sidewalk. It would leave small holes, not global-scale holes.
Marvel comics show this when the Hulk leaps. He leaves little craters behind him.
He naturally has the ability that was later produced artificially in “Legion flight belts” (and later rings).
He farts vigorously.
Just to expand on my earlier answer: it wasn’t until this month that they republished the Mandrake full-color Sunday comic strips in hardcover – but republish 'em they did, and I have 'em here, and in 1935 the caped do-gooder on the wrong side of a locked gate was all “when you can’t go through, you have to go over”, since Problem Illusions Can’t Solve equals “Rise In The Air And Float Over The Wall”.
And in 1936, our hero was still at it: a sabotaged trapeze act sends an innocent circus acrobat plummeting to his death – until “Mandrake instantly shoots up into the air with bullet-speed … and meeting Tim in mid-air, carries him to safety!”
(In between those strips, he rescues a kidnapped woman with some flying-carpet magic: “Mandrake, we’re – we’re in the air!” “Yes, Jana. This is much easier than fighting all of Indus’s soldiers” – but I’m not counting that; and, of course, he does a bunch of stuff with invisibility, and bright flashes of light, and making things seem to turn into gold – and I’m not counting that, either; I’m just saying, the man could fly; how? Magic!)