Ah, but you see, your rebuttal is SOMEWHAT flawed.
Moore taps into many old ideas, but like a good writer (see also: Shakespeare; yes, I'm comparing him to Shakespeare), he takes those old ideas and puts his own twist on them enough to make them new.
Examples: -Watchmen was originally going to be the Charleton characters, but he changed it around and made it his own. The ending, with tricking the population into world peace, was from an old Twilight Zone episode.
-Promethea takes the basic template of Shazam, makes it a woman and about woman power, fertility and most especially, the power & magic of creativity.
-Tom Strong was heavily influenced by pulp heroes like Doc Savage.
-Top Ten is pretty original, though, come to think of it. But you get my point.
A much better example of what the other commenter is looking for? Well, there was one creator. Unfortunately, his insane levels of creativity, combined with his worth ethic and ability to work with any idea has never been matched.
There's a reason why they called him the "King of Comics".