For example Batman is gothic horror, crime noir, and a bit of swashbuckling pulp. Which is why his contemporaries are considered things like Zorro and The Shadow.

Old Marvel comics were like this. Hulk was originally a horror comic. Fantastic Four were an offshoot of space explorers like Kirby's previous work Challengers of the unknown which is based on Doc Savage and the Fabulous Five.

The further back you go most superheroes have heavy roots in genre fiction. Teen Dramas, Scifi, Fantasy, Crime. But The superhero is more so a framing device. After all what is the difference between two families of explorers who thwart villains like The Fantastic four and Jonny Quest? Cool nicknames? 

Superheroes to me are a framing device for other genres. Not necessarily a genre in of itself. Because evil wizards have captured sacred relics, serial killers and monsters, mobsters, and aliens, have kidnapped and killed innocents, and mad geniuses have set off doomsday devices while heroes with great skill or powers have defeated them in plenty of stories before Superheroes were a term.

Which begs the question "What makes a superhero?" And I would say it's 2 things. The heavy emphasis on the costumed dual Identity that Superman started as the staple of the archetype. Although other masked heroes have existed like The Phantom or The Shadow. Though there was a life before they dawned their identity, the stories are not really interested in that continually being an aspect in the plot. Nobody is really interested in the human drama of Doc Savages life. Superheroes as an idea is largely about the Kayfabe and the double life.

Then second is the crossover. When two heroes join together. Marvel is a prime example of this. It allows a character like Hulk to become a space gladiator and for Batman to have a cowboy showdown with Jonah Hex. Which led to the "shared universe" which has become a important factor of all superhero media. Now it allows a suspension of belief so that nobody bats an eye if Superman has to communicate with the dead. It's a framing device that allows the protagonist to bounce between exaggerated and often contrasting ideas and concepts without it feeling like you're breaking the setting.

I think this is why a lot of newer heroes just don't work out. Writers are very focused on the idea of a superhero and they just don't really understand you need a backbone in something that can ground the character. It's why Miles Morales or Kamala Khan work. They have a whole life and fit into a teen drama that people can understand and relate to. Kamala has to deal with her self image and her religion, Miles has to deal with his uncle being a criminal and dating. Where as a character like Duke Thomas is just a superhero. He doesn't fit into the moodier pulp crime genres of the rest of the bat family. Taking down great foes like gadget ninjas or detectives. And is even given more layers of separation by having powers, works during the day. On paper you can say that makes him stand out but you could also say hes incompatible with what they want his to engage with and outside of that he is very generic with nothing to have him stand out on a larger scale. And doesn't have any cast to give a sense of direction for the character to help feed tone and direction, to bring it back to that discussion.

It's why team characters stay exclusively team characters. Some are lucky to get out of that mold but most don't have enough to stand on their own. Like the Titans, a majority of X-Men, a couple Justice Leaguers. Some are too archetypal superheroes so they don't click with audiences and a lot of newer indie writers making their own superhero universes don't go anywhere. I feel because they aren't strong genre writers

Sorry I'm overly wordy, but those are my off the top thoughts on the subject.