Superman is a very badly written character IMO. Very inconsistent, no logic nor science to explain him. He's basically a fan-driven hero who's cool if you're in grade school and grow out off eventually...
He probably has been written to have most powers a kid would imagine a super hero having.
Well... I remember there were comics that tried to explain Superman's powers as being psionic in nature and that he subconsciously used telekinesis to move things (but then they dropped that whole thing and left it up to the imagination).
Otherwise how could he lift a building by one corner, tilted at an angle? You set a building (especially one that's cut in half) at a 5 degree angle and it's just gonna collapse into rubble. Heck, a house can't support itself either. You just can't lift one... because there's nothing strong enough to hold it together.
Superman physics never makes sense. You just have to sit back and live with it.
He should have bugs in his teeth every time he flies...
He only has superspeed when it drives the plot. it goes away whenever somebody is holding a hostage at gunpoint...
His X-ray vision works HOW again? And why does 1/4" of lead block it, yet 80 feet of steel, 100 feet of concrete, and 6 miles of bedrock does NOT block it?
How does Superman fly? Does he use lift? What's his propulsion? I mean, seriously, what makes him go forward and stop and elevate, etc.? Newton's laws govern even superhero movement. How does Superman fly in space?
How can Superman metabolize earth food? If he's metabolizing earth elements, then his body has to be made of earth elements. Not Kryptonian elements. He's 10x the size he used to be when he was a baby, so most of his bones are made of EARTH elements. What are they? Calcium? Carbon graphite? To look like a human and be able to impregnate a human (as he does in some comics and movies), he must have sperm made from Earth organic compounds. Dude weighs a reasonable amount (under a ton, for example) and when he was a baby, his parents lifted him, so you can't pretend he's made of superdense material... Even if he were somehow "flying"/levitating to avoid crushing through the floor with his feet... how does that explain that the BABY version of him didn't weigh a ton, given that he never learned to fly until he was a teenager?
Superman makes no sense at all.
Plus when superman flies faster than the space shuttle (re-entry speed 16,250 MPH) his face and body should be white hot, from the friction (and blackbody radiation temperature is uniform across materials, so no matter what material he is made of, when he is 1700 degrees he's gonna be red hot...
...and he should be more like 3000 degrees or more, because unlike the shuttle, he does not have "ABLATIVE SHIELDING" (i.e. his skin doesn't evaporate away to cool him off... he's solid and stays solid, so he'll heat up to unbelievable temperatures).
Superbreath? To produce winds of 50 mph that are THAT COVER THAT WIDE AN AREA , the velocity of air coming out of that tiny orifice of a mouth has got to be in excess of the velocities from a plasma torch... i.e. again, he should be breathing FIRE at his lips.