Are Marvel movies cinema? Several media outlets have boosted this conversation since Martin Scorsese gently opined they aren't and Francis Ford Coppola more stridently called them "despicable". Semantically, I disagree with them but in spirit, for at least most Marvel movies, I have to agree, though I like several Marvel films.
For many people, the word "art" implies a level of quality along with describing a mode of human expression. I don't see it that way--I believe "bad art" is not a contradiction in terms. So I think it's perfectly possible to have "bad cinema", with cinema simply being movies. But Scorsese and Coppola are artists, not critics, so it's not incumbent on them to be precise with their critical terminology. They have the right, like Captain Marvel, to act on their feelings instead of their intellect, in fact it's part of their job, and it's a job many Marvel films won't do, like Captain Marvel.
Many Marvel movies don't feel like movies, they feel more like episodes in a long running television series. Ant-Man, Dr. Strange, and Infinity War don't really have distinctive visual styles or stories that stand alone outside the collective continuum of the series. Though I would argue the first Iron Man, the Guardians of the Galaxy films, and the first and third Thor movies, are all films with their own ideas, thematically and stylistically.
I guess I see the word "art" as being as neutral as the word "food". We'd be better off if we acknowledged most MCU films are junk food. One point a lot of people bring up in this debate is that, back in the 70s, genre films weren't seen as art, that arguably, as a gangster film, The Godfather was an example of how genre could not only be good art but high art. Of course, concurrent to this, in the 1970s, Deconstructionists were beginning the academic movement which has become an institution to-day, one that argues that good and bad are entirely subjective and meaningless when it comes to art. To a Deconstructionist, it's just as valuable to analyse "Manos" the Hands of Fate as it is to analyse Blade Runner. For everyone else, Star Wars posed a solid argument that great works of art could exist in the realm of genre fiction and so were worth attention and acclaim. But it's worth remembering that Star Wars is a better movie than Laserblast.
Of course, I'm pulling examples from Mystery Science Theatre 3000 for bad knock-offs, and unlike the standard Marvel gruel, these films were never popular. But I suspect most Marvel movies occupy the place Roger Corman movies once occupied in the 60s, a director with whom both Scorsese and Coppola worked early in their careers. Churning out cheap horror, science fiction, and exploitation films, Corman's films left a lot of space, a lot of blanks for the audience of teenagers to fill in. Into this void would be the opportunity for making out. To-day, instead of making out, the average teenager may be more likely to text. In any case, yes, most Marvel movies don't provide a full course meal to the mind and spirit but sometimes all you want is something cheap and greasy. Like popcorn, for example. Though I think Marvel movies could stand to include more grease.