Superman's powers aren't simply that he is "Faster than a speeding bullet! More powerful than a locomotive! Able to leap tall buildings in a single bound!" His real power is so much greater. He is able to save people from great falls by simply catching them midair, even though the laws of physics say such a move should break every bone in a person's body. He can lift huge objects with a single hand, even though these objects should crumble from so much force exerted on such a small area. He can even turn back time by simply flying backwards around the world.
As a result, you must conclude that Superman's powers aren't simply limited to super strength. Instead, he must have a truly awesome ability to manipulate reality and the basic laws of physics when it suits he needs. Since Superman never acknowledges this is his true power, he must be doing it subconsciously. This then begs the question, just how great are Superman's powers, and to what extent has he been using them?
In the DC universe there were basically no superpowered entities until Superman came along, but within a few decades the planet was overrun with them emerging from everywhere. It stands to reason that maybe this explosion of powerful villains and heroes may have all subconsciously been the doing of the incredibly powerful Superman. After all, what would an alien with near limitless power subconsciously wish for if he was raised by a nice couple from Kansas to be a honest, dutiful, and just young man? He would probably wish to be able to blend in with humans perfectly (which is why an alien could look so much like a human, even though it is basically a statistical impossibility). He would probably wish for powerful friends that would understand him (the Justice League). He was also probably wish for challenges, excitement, admiration, and ways to prove himself (by fighting and defeating his superpowered enemies). Almost everything in the DC universe, including the frequent city-destroying battles, could unknowingly be Superman's doing.
This is where Lex Luthor's potential heroism comes in. He has no powers, and unlike most DC villains his current existence on Earth seems to predate Superman coming into his own. He is simply one of the smartest and richest people alive and probably was basically the same before Superman began heavily distorting reality. Luthor is a relic of the old world, the pre-Superman world -- the real world.
This along with his incredible intelligence and position give Luthor the unique ability to sense something is truly wrong. While even Luthor can't completely see through the distortion, he is able to understand the cause of this great wrong and what must be done. This is the source of Luthor's seemingly irrational hatred of Superman. While Luthor can't fully explain it, at some level he knows that Superman isn't Earth's one defense against a constant stream of monsters. Superman is the one wishing them into existence.
From this perspective, Luthor is the ultimate hero: a mere mortal trying to save his world from the acts of a near god when no one, not even Luthor himself, can fully understand why he fights.
My first sci-fi novel, Cobalt Slave, is now on sale at Amazon.