That while wasn't long. In less than two years, Superman was rebooted with a loving, year-and-a-half redefinition by Grant Morrison.
Three years later, that Superman is dead, and we have been told by the mysterious Mr. Oz that the last Superman was maybe never Superman at all.
But we have the previous Superman back, which may mean that Secret Origin is once again the origin of the main Superman. Even if so, his reality is now (pending future events) very messy, with his life from birth through adulthood having been spent in his home dimension and the rest of his life on a new dimension without "his" Batman, Wonder Woman, Justice League… even his Krypton or Supergirl. Only his Lois Lane and his son made the trip with him, so the new world has two Lois Lanes. It also has a Clark Kent who is not super-powered, is not Superman, and has memories of meetings with Superman that Superman doesn't have. Everyone in this world knows that Superman is… or was… Clark Kent.
It's messy. And far messier with the addition of two other supermen, with Lex Luthor wearing battle armor bearing the S-symbol and, in Shanghai, Kenan Kong starring in a title called New Super-Man. So there are four living men, plus one dead, sharing some aspect or another of the identity of Superman. In addition, August will bring Superwoman #1, with Lois Lane getting the powers she always wished for.
All of this hearkens back to the past in many ways. When Superman died in a 1993 story, he was succeeded by four alternate versions of Superman – including the Eradicator, who is the focus of the current plot in Superman – none of whom was the literal incarnation of the dead man. The event in which the dead Superman returned to life was called "Reign of the Supermen," a titular reference to Jerry Siegel's 1933 story about a Bill Dunn, a regular man who had been given super powers artificially by a mad scientist. This title was referenced in 52 in an issue dubbed "Rain of the Supermen," in which ordinary people given powers by Lex Luthor fell to their deaths when he suddenly switched off their powers. All very ominous for China's new Super-Man, who, in getting his powers from mysterious scientists, is perhaps following in the footsteps of the oldest Super-Man. Lois Lane getting superpowers to become Superwoman was originally depicted in 1943. Is DC revisiting every past year that ends in a '3'?
If 1993 is the playbook for what is happening now, the non-Superman supermen will serve as good supporting characters for DC to work with and the real Superman will step up. Certainly, the Superman who's married to Lois is the individual who seems ordained to fill the role, but we also know that he's going to be reclassified in some essential way, with Mr. Oz telling us in DC Rebirth #1, "You… are not what you believe you are. And neither was the fallen Superman." With Mr. Oz alluding to that Superman's death as a "tragedy" (the air quotes are his, corresponding to a snarky tone of voice that we can't hear), we can take it that Superman's falling was not dying in the conventional sense, and so, the New 52 Superman must be alive or in some sort of limbo. If he's anyone whom we've seen living, then he's likely the powerless Clark Kent who is running around being enigmatic, seemingly on purpose.
When Grant Morrison told the tale of the New 52 Superman in Action Comics, he posited that the New 52 Superman was the individual who fought Doomsday and died – who was the same Superman as pre-Flashpoint, but altered. This wasn't clear until Action #16 when Jimmy and Lois stood beneath the golden memorial statue with an eagle perched on Superman's arm. Lois said, "Superman died right here." Jimmy responded, "Yeah, and then Superman saved everybody, remember? He beat the bad guy. He came back from the dead." Yes, Jimmy, we do remember. Are we supposed to? Is DC being true to what the stories have told us before? They're preparing some intriguing reveal that will tell us that the identities of the dead New 52 Superman and the revived pre-Flashpoint Superman aren't what everyone thought, and that will give us the Rebirth take on Superman, someone whom we're seeing in action (and in Action), but whose true nature is still unknown to us and to him.
There's a new story in progress, though, one that surely wasn't in line with Morrison's plans. Now we have a Clark Kent who is just as suspicious about Superman as Superman is about Clark Kent. And, in a fragmentary conversation during the battle in Action #959, Clark indicates that he seems to know more than Superman:
Clark: You'll "save me," is that it? Like you did before?
Superman: No idea what you're talking about.
Clark: Months ago. When you sent me into hiding.
Superman: I want to help you, but I don't kn-
Obviously, the timeline is fractured. Clark was plucked from it at a different moment than Superman. This Clark experienced a meeting between the two that this Superman either doesn't remember or didn't experience. Clark is resentful of how that all transpired, but here he is, alive. And we know that the fallen Superman's fate is not a "tragedy."
How, at the end of this, are the creators going to put all of the crayons back into the box and give us a Superman whose origins are not torturously complicated? If married-to-Lois Superman isn't who he believes he is, and they want to make the origin blend into the post-Flashpoint, post-Rebirth world, then they may be planning to tell us that he is the post-Flashpoint Superman, but older. If the falling of the fallen Superman was not a tragedy (with a snarky tone, in air quotes), then something else happened to him. For the messy situation with four living Supermen, a dead Superman, and a Superwoman to resolve itself, we're going to have to start learning that some of the multiple Supermen are evidently not different men but the same man tumbling through some timeline or inter-dimensional voodoo. Perhaps dead-Superman, living-Superman, and Clark Kent are all (or, at least two of them) the same individual at different moments in his life. Perhaps the New 52 Superman didn't die but grew a little older to become the Superman who's now married to Lois. Wally West has kicked off Rebirth by telling us that years of the heroes' lives went missing, and they lost, among other things, love. The simplest solution to the mystery of the multiple Supermen is that they aren't multiple, after all.
Given these clues, my take is that is the Superman who is now fighting Doomsday is the Superman who was born on this universe's Krypton. What appeared to be the death of New 52 Superman, wasn't. He somehow lost his powers and was sent into hiding as a powerless Clark Kent by Superman, who – due to some sort of timeline fracturing – doesn't remember the past few years correctly. I think the resolution to the mess is that DC will tell us that it's not a mess, just a good story, and that there was only one Superman all along.