Duff, WTF man?
You are treating this movie as a first run kind of movie. While it is true that it is not necessary to watch the previous movies, it is a much better experience if you do. Or at least know something about the characters. Like Captain America isn't just some random dude with a C and plain shield.
Geez, you might as well watch Star Wars Return of the Jedi first without watching the 2 prior films.