There is no definition of "superhero fiction" that holds water. There are no themes and styles exclusive to "superhero fiction" and every theme and style is included within it.
I.e. Everything is Super. And when everything is Super nothing is.
There are always blurring of boundaries of course. Also something doesn’t have to be exclusive in order for it to be typical of a genre. A genre is usually typified by a range of features, some or all are usually present.
Here are some features usually present in the superhero genre...
- Specific Superhero characters
- A suite of Supervillains that don’t as a general rule die, or at least not for long.
- Secret identities/dual personality
- A lack of permanent death
- Continuity of the same characters across several incarnations/timelines/universes
- Cross Overs Superhero stories
- Borrowing elements from other genres - 20th C Crime into Galactic Sci-fi (where a lot of the confusion stems from)
I would say of these common themes the majority are not common for a typical 5e game.
Most villains are dead at the end of a module, with the exception of a small few rarely encountered ones, Tiamat, Accerak etc.
Very few 5e PCs maintain dual identities.
While raise the dead is sometimes used. It isnt ubiquitous and it is heavily dependent on the game world, levels of campaign, and style of play.
Rarely do players play the same PC in different incarnations - certainly in my experience.
The nature of leveling means PC groups are usually created for a campaign and stay in that campaign. Rarely do PCs chop and change between multiple campaigns.
For that matter I’m not sure genres cross over anything like they do in Superhero fiction. It’s rare that Sci-fi themes interact with medieval fantasy. Barrier peaks and Iron Gods are very much an acquired taste!
With all these things, you can choose to play the game that way. But it is by no means standard 5e.