WARNING: READ CAREFULLY; FEEL FREE TO AGREE OR DISAGREE
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Holy xxxxxxx hell.
So I just read this post. This ENTIRE POST...
...and holy hell did AhsokaTanoJediKnight have a lot to say, (btw, this user was once harrassing admins on my home wiki too, but compared to this, the insults have been a lot more racist, and I'm not kidding. I just began to ignore all of it after a while).
So allow me to give my side to this argument: do superheroes like the main Trinity, Green Lantern, Aquaman, exist in the Arrowverse's Earth-1? Well, I'm torn, specifically towards the whole sub-argument about Krypton. I have strong reason to believe that Krypton did explode, and the Earth-1 Kara Zor-El has yet to make herself known, so I'll have to (begrudgingly) agree with Ahsoka, but it isn't for comicbook physics reasons, it's for marketing and conventional reasons in the inner workings of the CW showrunners.
A thing that is surprisingly missing from Supergirl is the presence of Kara's slightly older counterpart (sorry, I don't like using doppleganger because to me it's just another word for clone), Kara Zor-L/Karen Starr, or as most people recognize her as: Power Girl. Although Alura In-ze is essential to Kara's journey to become the Maiden of Might, Power Girl is equally as important as technically she has been through the same journey. There are multiple instances where the two are interacting and Kara teaching Kara. So in terms of convenience, Power Girl could in fact be the Supergirl of Earth-1. It would certainly make for interesting situations in other shows of the Arrowverse, like if Barry could talk to an older version of his best friend that is native to his universe & Earth (and therefore not as naïve as Kara on Earth-1), and find how different or mature she is. It would be like she's a different person entirely. It would be something along those lines, I'm not a genius when it comes to personal engagement between characters. Or maybe, Power Girl can come from a different, unseen universe entirely, as Earth-X being Earth-53 instead of Earth-10 proves there are more than the 52 main earths. But in terms of making for interesting character reactions and mature storytelling, Earth-1 could be one of the more likely candidates.
However, just because I am leaning to the argument of a destroyed Krypton in Earth-1, DOES NOT mean that I agree with EVERY SUPERHERO existing in EVERY UNIVERSE, in EVERY MULTIVERSAL CLUSTER.
To understand my counter-argument, we have to look at the way we view our multiverse. Our multiverse theory says that a new reality is created with each choice. It calls back to the Schrödinger's Cat theory, that says that if you put a cat in a box with a vial of poison, one of two things can happen (the vial breaks and kills the cat; the vial doesn't break and the cat lives) and both these things enter their own quantum state, birthing a new reality in the process (then the theory talks about someone opening the box and the realities collapsing into one continuum, but hey, we're nowhere near there yet). So basically, the multiverse is full of alternate choices that each one of us make, some of them sharing the same reality. Now, the DC multiverse is a little bit different...
...and by that I mean completely.
In the DC multiverse, there are an established 52 earths that each contain one scenario: Earth-0 is the main universe, Earth-1 is the Silver Age/Ultimate universe, Earth-2 is the Golden Age universe, Earth-3 is the Anti-Matter/Evil Universe, etc. The main earths featured in most titles include 0, 1, 2, 3, 5, 6, and 10/X. Then there's the elseworlds titles like Earth-19 (The Steampunk universe), Earth-21 (The New Frontier), Earth-22 (Kingdom Come), Earth-50 (Justice Lords/Injustice), and the main focus of my current point, Earth-11 (The Gender-Swapped Universe. In the comics, Earth-11 is a world where the Amazons left the island in the distant past and spread their ways to the world, inspiring more women to take leading roles in the world. Okay, but how does this constitute for Clark Kent to becoming Laurel Kent? The Amazons spread their ways on Earth, not on Krypton. What made Hippolyta shrug her shoulders when instead of having Diana, she had Dane? Some of these choices aren't even choices. So to be clear, each earth is RADICALLY different to one another. They are somewhat parallel in terms of planets and lore and species, but a much more displaced y-intercept in terms of history and culture and choices. The same thing applies for our Arrowverse here; how many choices were made differently for the Nazis to have developed the atomic bomb faster than the Allies to win WW2 and create Earth-X? What happened on Earth-2 to create advances in technology but retain a 1950s culture? There are too many events happening with differing probabilities per reality. So therefore it is highly possible that the Arrowverse Earth-1 is one of those universes where the events leading to the Wayne murders or Diana leaving Themysciara did not happen. Hell, we've got a prime example on the Flash! S.T.A.R Labs, before being the Flash's base of ops, was well recognized as being a part of Cyborg's lore. Yet, because of the Particle Accelerator ruining the company indefinitely, there's no chance of events happening leading to Silas Stone technologically augmenting his son to save his life. But what exactly protects or shields the Arrowverse from the influence of other universes to implement the likes of Superman, Batman, or Wonder Woman? Well...
So let's look at another brand, and this'll explain what I meant by 'multiversal cluster'. Who remembers Transformers? I sure do, and being a fan, I'll tell you its multiverse is really fascinating. See, because Transformers is a franchise, it has many different variations of one brand they are promoting. Because of this, the visions usually clash and are not compatible, like the original G1 cartoon and the G1 Marvel Comics; both are based on the same toys, but tell slightly different stories. Their fanbase has a way of organizing this mess, especially with the implementation of new brands like the movies or the Aligned Continuity. They call them UNIVERSAL STREAMS. It focuses on variations of what appear to be the same reality, and the differences go from subtle to very different. They have them for each of their brands; the movies have one stream for each of the movies, one for the tie-in comics, and even one for the stupid promotion in stupid online games for stupid prizes-I'm going off-track! Each of these brands are then categorized and referred to as MULTIVERSAL CLUSTERS. I know that DC and Transformers are two VERY different franchises, but you can't deny that this stuff makes a lot of sense without thinking about it a little. The Arrowverse calls itself Earth-1, even though we know that's not the case because there is another earth out there called Earth-1. There are so many of these earths, it can be confusing to categorize, so much so that you end up like AhsokaTanoJediKnight who can't tell that the comicbook multiverse and the television multiverse aren't the same thing. But when you consider the 'Cluster' theory that accounts for different sets of Earths with somewhat similar properties but can't exist in the same space with Earth-0 due to great differences, you begin to see how it might work. The Arrow Multiverse is a separate entity from the comics or movies, and exists in its own little bubble that takes some aspects from the main multiverse and leaves out some. Hence why it is separated from most of the DC canon.
So to wrap it up, the theory of different streams being the ones that have different histories leads to one thing: Because the Arrow Multiverse is a multiversal cluster with different earths that have their own universal streams, it is separated from the rest of the DC canon (appropriately, it's an elseworld story). Some aspects from earths outside the Arrow's continuity have bled over into this cluster, like the existence of a Superman on Earth-38. But other elements, like Batman or the JLA have proven to not exist at all because of this separation, even though they can be found everywhere else. My theory may be totally wrong, maybe even worse than the next guy's, but it is a theory, one where I'm merely trying to craft an explanation to a good question with a variety of comic book reasoning from various sources, and to show that AhsokaTanoJediKnight is a little short-sighted for not considering these kinds of possibilities. Maybe not as in-depth as I'm going, but perhaps something similar in thought.