It's not for me to say, but I can tell you what I experience from the title (in a long, non-sequitur rambling as Miracleman tends to make me shiver when I think about it).
In Nietzhe's "Thus Spake Zarathustra" the idea of God being dead was that if he was indeed dead, then Man must strive to replace Him. In fact, Zarathustra, the superman, destroyed the human man merely by his presence.
What we see in Miracleman is very much that. Miracleman appears (and even the Warpsmiths say this at one point) and soon, the normal man is made not only obsolete, but as we can see by #16's end, but the normal man is completely destroyed (look at what happens to both Mike and Liz Moran when Winter appears). Miracleman, to me, does not say man can be god, but man IS god, and by waking up from the slumber of mortal flesh, we realise that potential, and leave what we had before, our crutches, behind. The waking destroys the dream, does it not? So does the god destroy the man.
Nietzche's idea of man having to ascend is very heretical because it attempts to remove God from the equation and thus, leads to hubris and madness. The religions of the world preach the same message - the ascension of man and its inevitable reward - but do so with the Godhead figure to create humility, an important lesson that the powerful must understand. But that humility is also turned to fear and used for control. Nothing is ever truly perfect.
So, in this sense, Miracleman is a deeply spiritual story, discussing very religious themes - about man and god, their relationship, how one perceives the other, and so forth. The title is very much about the relationship of the mundane and the divine.
And no other genre so epitomizes that relationship than the superhero, where the protagonist is mundane (secret identity) and divine (super hero).
At least, that is what the story's conflict is about. How you see that conflict, be it a message for improvement, or perhaps that gods are terrible and terrifying, or that there are no gods, or that we are all gods - well, that is up to you. The conflict though, is god and man. Life and death.
To confront eternity, as we do so fully in Miracleman, forces one to confront our own mortality. To me, this is the most powerful part of Miracleman, and I feel that confrontation with death each time I read it. But the beauty of Miracleman is it does not preach fear of survival, but the acceptance of death, and the understanding of eternity.
And it does this through powerful dream imagery. Of life and death as a dream. The dream of humanity. That one day, we must wake up from this world of and see it for the remarkable miracle that is. The miracle that we are. The divine revelation. This life we lead is not the only life, the only world, and there is so much more. Be wary of the nightmare.
To you, I wonder what it says. To you, what defines it? To me, Miracleman says two things that will probably continue to touch me until the day I die.
"Oh Earth, look up."
"Sometimes, I just wonder."