Have we reached peak superhero?

[Sacred Knight]

In the movies, absolutely. There I think we're past peak and well into decline territory.

[achilles]

That's not the reason the Green Lantern movie failed. People cited weak acting, terrible CGI, an unlikable protagonist and a wasted premise as reason for their disatisfaction. If anything, we can see that self-contained superhero movies can work with Wonder Woman, Aquaman, Shazam and Brightburn (for examples outside of the Big 2). Audiences may like shared universes but that doesn't mean they don't like self-contained stuff either. I wouldn't even say the GL movie was done like a Richard Donner film given it was clearly setting up a sequel as well as a potential shared universe (that's why Amanda Waller is present).

Not to mention that the bad guys were a dude with a giant head in a wheelchair who screams a lot, sounding like a little girl, and a cloud of CGI space vomit. Basically, it was a very bad movie. That...alone is why it failed.

[Agent Z]

There are movies which have some or all of that and succeed commercially, so it's not a sufficient reason why a toy commercial for kids didn't sell.

Kids have been less and less interested in toys for a long time now. The fact that a lot of kids think Green Lantern is a black guy named John Stewart was also likely a factor. And while movies with those problems do succeed, there are plenty that still fail. Green Lantern isn't the first movie of it's kind to flop. It's not rocket science.

As I said, you need to work by generating novelties. Wonder Woman had a female superhero, Aquaman was a character people knew of but never saw on screen. Shazam was "Big" as a superhero movie. Brightburn is a horror film.

I'm not even sure if being novelties is all that important. Audiences watch movies and t.v. shows with varying degrees of similarity. Execution matters more than anything else. Wonder Woman wasn't the first female-led superhero movie (Diana's not even the first female superhero), it was simply the first one that was competently made. Captain Marvel made even more money than Wonder Woman.

Execution matters more than novelties to audiences. As they say, "there's nothing new under the sun".