It is very easy in 2018, some 10 years and 18 movies into the Marvel Cinematic Universe, to take it for granted.
The Avengers combined all of those challenges in one film in a way that was basically unprecedented in cinematic history.
It’s particularly striking because it comes directly on the heels of Captain America: The First Avenger, where Cap (Chris Evans) wore one of the coolest costumes in the Marvel Cinematic Universe.
Marvel divides up their films into different phases; The Avengers is the final film in Phase 1 after Iron Man, The Incredible Hulk, Iron Man 2, Thor, and Captain America.