A Kind of… Normal Narrative Technique?

The Breakfast Club doesn't involve flashbacks or a "fractured narrative" (a la Pulp Fiction) or anything like that. It's just a good, old-fashioned narrative. But it doesn't focus on just one main character—it focuses on five. So you couldn't compare it to a third-person limited perspective. It's observing all the characters, which would make it more like a third-person omniscient perspective—if you can say that about a movie, since it doesn't really take us into anyone's interior monologue.

However, Brian begins the movie reading his essay in voiceover and ends the movie in the same way—though the voices of the other four chime in at that point too, reading off the names of their respective stereotypes. So you could argue that the lesson Brian personally learned frames the whole movie—not that this makes Brian the main character or anything, since everyone else apparently learned the same lesson too.