Apparently, the death of Superman and the absence of Hal Jordan don't matter.
There are certain concepts of justice that aren't subject to politics, laws, or retcons. These concepts transcend eras, cultures, and hashtags. They act as the binding ideals of humanity. Debate over these ideals is never-ending, but these debates are necessary to provide context to these ideals. That's what makes the goals of the Justice League so daunting, but so meaningful. Without this context, they're just another team of superheroes hoping that their movie tops The Avengers.
In the aftermath of DC: Rebirth and Darkseid Wars, the context of the Justice League is in flux. It's not just a result of changes in the lineup and the latest (albeit no-so-greatest) death of Superman. The overall mood and tone of the Justice League is changing. The New 52 utilized certain themes, attempting to be more mature than it needed to be at times. Justice League Rebirth #1 attempts to refine these themes in a way that doesn't feel like regression.
If there is a kryptonite to the new direction of DC: Rebirth, it's this perception of regression. There's no denying that the New 52 had its flaws. The post-Crisis status quo had its flaws too. The challenge with DC: Rebirth is to not come off as exchanging a new flaws for old ones. In the end, it leaves things just as flawed as before and sets a dangerous precedent that DC will resort to Mephisto-like tactics to tweak its continuity. The tweaks in Justice League Rebirth #1 are meaningful in the sense that it moves the narrative forward. However, the progression, in terms of meaningful context, is lacking.
The purpose of the narrative is simple. It puts the Justice League in a situation where they need Superman and two new Green Lanterns, Simon Baz and Jessica Cruz, to join their ranks. It succeeds in this respect, but with limited drama and little sense of progression. Absent of any context and such a simple narrative works as well as any story that involves superheroes fighting giant monsters. It's a narrative that the Justice League handles whenever Lex Luthor has too much free time. Within that context, however, the story lacks impact.
Taking a step back and looking at the bigger post-Rebirth picture, we see a Justice League that just suffered a terrible loss with the death of Superman. They just lost someone who helps them come together in their first battle against Darkseid. It's a big loss on so many levels. They didn't just lose a teammate. Wonder Woman lost a lover. The world lost an icon. It's a hole that can't be easily filled with clones, cyborgs, or relatives. DC already tried that in the '90s and, like the Batman movies of the time, it didn't work.
Bryan Hitch tries to highlight the impact of this loss in the battle against a generic, city-sized monster. That loss, however, is undercut by the arrival of the post-Crisis Superman, who has been waiting in the wings since Convergence. He looks like Superman. He talks like Superman. He is pretty much the same Superman that the Justice League remembers, rendering the death of their former teammate to a mere inconvenience. This being Superman, the gold standard for superheroes for eight decades running, that's downright callous.
The arrival of the new/old Superman effectively overshadows the arrival of Jessica Cruz and Simon Baz. Their arrival doesn't contribute much. They just show up to aid a Justice League that lacks both Superman and Green Lantern. They lack Hal Jordan's attitude, but bring some needed firepower. However, that's all they bring. While they do have potential, most of this potential goes unrealized.
Once again, the situation is reduced to convenience. The Justice League lacks a Green Lantern. They end up getting two, which seems like a bargain until they fail to bring anything new to the table. It's the same issue with the new/old Superman. They're basically conveyed as spare Lego pieces, interchangeable with their predecessors and allowing the Justice League to continue as though nothing happened.
This is the flaw that the larger context that Justice League Rebirth #1 exposes. The significant losses that the team is still processing suddenly becomes irrelevant. The death of Superman and the absence of Hal Jordan no longer matter. Rather than doing justice to those losses, the story focuses entirely on filling the void with other characters. The drama, the relationships, and the dynamics within the team are an afterthought. The goal of Justice League Rebirth #1 is to just give the team a full roster again. It succeeds in this respect, albeit in a very shallow way.
That's not to say that Hitch's narrative is completely lacking. The battle against the generic giant monster has more depth than a typical Power Ranger rerun and even hints at the larger threats that the Justice League will face moving forward. It does highlight just how important it is to have someone like Superman and Green Lantern in their ranks, but the ease with which they fill those ranks still undermines the drama.
At the very least, Justice League Rebirth #1 offers a fairly concise story that re-establishes the Justice League as a complete team. Unfortunately, it does so in a way that feels shallow and forced, undermining any drama or upheaval that may have emerged otherwise. It's a missed opportunity in some respects, but it does move Justice League forward into the post-Rebirth status quo. It still comes at the cost of utterly undermining the death of Superman. Whether that cost is worth the results is debatable, but given the context of Rebirth, it's a lopsided debate at best.