I have answered a similar question a while back. The short answer is: yes, there are other superheroes in the "Spider-Verse".
To understand why the answer is a pretty simple yes, we need to understand that when it comes to marvel, pretty much all marvel media is part of the marvel multiverse. When it comes to the multiverse, due to the MCU and the Spider-Verse movies, it's getting a little bit wonkie. This is because the MCU declared itself Universe 616 even though the comic main universe already is Universe 616, and the universe Miles comes from in the Spider-Verse movies is also considered Universe 1610, which in the comics is the Ultimate universe (where Miles also first appeared in the comics after it's Peter died due to being shot by the punisher and right after having to fight a couple of villains who escaped from Prison, including Norman Osborn in his goblin form trying to kill him and his family). Funny enough, the Spider-Verse movies even "made fun" of the fact the MCU declares itself as 616 when Miguel O'Hara (Spider-Man 2099) said
Now, don't even get me started on Dr. Strange and the little nerd back
on Earth 1999999
referencing the movie Spider-Man No Way Home and it's Multiverse event.
So not only is it theoretically true that this movie is part of the Marvel Multiverse, the movie even references the multiverse (this is not the only occasion. The "Canon Events" scene utilizes scenes from Spider-Man (2002), The Amazing Spider-Man and from the comics to show "Canon Events"). So yeah, they reference at least 2 universes in which other heroes exist. Comic 616 and the MCU 199999.