FWIW I haven't seen the Lighthouse and love Iron Man as a movie, though I wouldn't call it deep as much as effective. And there's something to be said about art that manages to be effective regardless of its profundity or whatever arthoes would designate as true merit

I'd say this is like asking if cinema is art while comparing something like The Lighthouse with Iron Man, or painting when it's the Mona Lisa vs furry porn. I suppose you can argue these are all art simply by being units of a medium, but their merit is clearly obstructed by their commercialization