Initially, it would seem that placing the host of a children's Edutainment show as the main character in a Cosmic Horror Story series like this would mostly be for the sheer Mood Whiplash of it all. However, Pibby may just be the perfect character to stave off the Eldritch Abomination that ate her show and countless others for one very important reason: she can learn. Unlike shows geared towards older audiences, which usually require numerous episodes or even entire seasons for their characters to develop, or Monster of the Week-type shows that rely on Negative Continuity to maintain the status quo for the next episode, Learning With Pibby is all about educating its young audience about new ideas and concepts. As the host of such a show, Pibby has to be just as receptive to new experiences as her audience is, which would go a long way to explaining why she is quickly able to adapt to hopping through all of the shows she goes through, and turns from an innocent Broken Bird who doesn't know what blood is to a Little Miss Badass who fights back the Glitch with swords and guns as big as she is over the course of (presumably) a single season.
The three main characters are based on different character archetypes that are now seen as obsolete:
Pibby is, of course, the lead character from a preschool edutainment show. While edutainment shows are still around, they're also something a good chunk of the population will outgrow at any given point of time. This is especially true because shows for slightly older children (kids in elementary and secondary school) have become increasingly more mature in how they handle storytelling, their messages, and their narratives.
Also, her edutainment show's format is based on other shows that were popular in the 1990s, but have since been outdated.
Alloy Boy is a Kid Sidekick to a superhero. Superhero comics have been in decline, and while the genre is still prominent in the 21st century thanks to live-action movies and TV series, most of them don't feature a Kid Sidekick character. At the very least, if they are around, they'll usually be older than in their original incarnations and/or become their own hero, which is likely done to avoid implications involving the sidekick being a Child Soldier.
Disney Classic Villain-type characters, whom Melira is based upon, simply don't exist anymore. Since the 2010s, Disney themselves have been moving away from the "queer-coded villains who do stuff For the Evulz" characters in favor of more socially acceptable villains who have more depth and a Freudian Excuse.
Viewers noticed that there was one show during the April Fools Day event that the darkness wouldn't touch: Joe Pera Talks With You, probably because it's just too pure.
This might also explain why Muriel is fine in the pilot.
This may also explain why Pibby lasts far longer than her friends have. Preschool shows like Pibby's usually have the title character be the wiser, or at least more innocent and reasonable one that helps their more flawed friends learn lessons. (I.E. Mickey Mouse Clubhouse, Handy Manny, Ni Hao, Kai-Lan) On the other hand, Bun Bun has fears and flaws that the Darkness can exploit. The same can be said for its other victims. The Finn here is younger, as he has both his arms and his old sword Scarlet, meaning that he's still a Hormone-Addled Teenager with not as much development, and the same goes for Jake; Fred Flintstone, George Jetson, Buttercup, and Gumball aren't bad people, but they have a selfish streak; Bugs was a lot more of a dick in earlier cartoons (it's the reason Yosemite Sam was made), and Porky has a temper in many cartoons, not to mention at least one version of him being aReformed Bully; Rick and Master Shake are genuinely awful people; Scooby and Shaggy have fears like Bun Bun; Amethyst has angst over being defective, and as Sugilite examplifies, is pretty violent; and Unikitty outright admits in The LEGO Movie that she supresses unhappy thoughts, which isn't healthy.
From Pibby's point of view, the glitch completely derailed The Eric Andre Show by making Eric unknowingly commit murder. To the uninitiated, it briefly looks exactly like that. But fans of the show — and the meme — will know that the glitch was unable to make the episode any more twisted than it already was.
This may also be why Rick doesn't seem affected.
During Adult Swim's April Fools 2022 broadcast day, Pibby herself shows up during some of the commercial bumps. In one of them, she asks the audience for help, but is distressed at the fact that the audience doesn't respond. Makes sense, as Pibby is from a preschooler Edutainment show, which is usually structured to talk to its young audience so that they can all learn together. No such programming would be on Adult Swim, with far older audiences who wouldn't really have any reason to respond verbally to the shows they watch.
As discussed in the Characters page, supplementary material claims that the Darkness would have used Bunbun as its mouthpiece. At first, this may seem like an odd choice for it. It's already assimilated hundreds, if not thousands, of other characters so why out of all the characters it could have used, why a preschool bunny? Why not someone more iconic like Bugs Bunny or Scooby-Doo? Or maybe someone heroic like Finn or Bubbles? Well, assuming that The Darkness is sentient or sapient, it probably recognizes that Pibby is the main character and thus the one most capable of defeating it and destroying it, so it uses her best friend to demoralize her and lower her chances of succeeding and saving the day.
Why is the Darkness represented as glitchy? A glitch is an error in a system, something that's not meant to happen, and that corrupts data. The Darkness suddenly intrudes in the cartoon's (and even real life's) worlds and corrupts the characters in there, which isn't supposed to occur in their shows.
Notably, only the main characters of the featured shows appear assimilated by the static in the trailer, and a sidekick and villain managed to escape alongside Pibby. This begs the question of what happened to the numerous side characters and villains of all the assimilated cartoons. Finn's mother, Jake's brother, or BMO? PB's girlfriend, Marceline? Gumball and Darwin's parents, siblings, and friends? Unikitty's friends from both her show and the movies? The other Looney Tunes aside from Bugs, Taz, and Porky? Fred and George's wives, children, and neighbors? Daphne, Fred, or Scooby's nephew? The other Gems or Steven? The Powerpuff Girls' own father? Did they escape the corruption? Did they get assimilated offscreen? Are they just... gone?
Even if they did escape, now they're going to have to live with Survivor's Guilt and deal with the fact that for all they know, a dark force has taken over and defiled their friends and loved ones' corpses, which they'll have to put down.
Similarly to Super Smash Bros. Ultimate before it, there's a bit of horror when it comes to just how far the Darkness' attack goes. Can it only affect TV shows and movies, or does it go beyond that? Remember, there's a high chance that OK K.O.! Let's Be Heroes could be a part of the TV world, and that had a crossover with Sonic the Hedgehog. Remember, Sonic is in Super Smash Bros., and considering how many connections that series contains...
Dear god, what happens when the Darkness encounters Galeem and/or Dharkon?
Galeem would probably try to put it down, and Dharkon would probably want an alliance and/or to somehow control it.
In the manor scene, two child-like dog characters can be seen with the main three. In the next scene, they're nowhere to be found. What exactly happened to them?
The boy dog of the duo (or at least a character who looks a LOT like him) is shown corrupted next to Bugs Bunny when Bun-Bun emerges from the giant static blob at the end of the trailer, so it's safe to say the Darkness got to them, and likely everyone else in Melira's world.
The "QUIET" scene is indeed one of the funniest moments in the pilot. However, when you think about certain detail, it's not without a dark implication: the narrator's voice upon repeating Pibby's word out loud (being from an educational show) is not that of a normal family-friendly-sounding voice, but instead a distorted high-pitched voice that sounds more like one of a malignant computer AI from a horror work. It's as if the Darkness also infected the narrator from Pibby's show, and he's now one of the many servants working for it, so him repeating what Pibby said out loud sounds less of an involuntary move and more like a form of signal to call the corrupted Finn and Jake who were just patrolling the area, using the educational gimmick from his show as a way to do just that.
Despite all the corrupted heroes showing up, most villainous characters aside from Melira are nowhere to be found, which makes you wonder if there's a possibility of characters like The Lich or Aku (two already hard to kill Eldritch Abominations in their own right) being either left on the loose or even overpowered and assimilated into the corruption threatening everything.
, the brain is an information processing system that works similar to a computer.