Captain America 1 and 2 also essential.

First Avenger - Introduces Howard Stark, Peggy Carter, the tesseract, Shield's formation, Red Skull, Bucky Barnes

TWS: Brings Falcon, TWS and delves further into Steve and Bucky's history, develops Steve and Natasha's relationship, sets up Civil War, exposes SHIELD/Hydra

>>it was like leaving game 6 after the home team had a chance
>to end the series, but they lost and now you know they gotta
>go on the road for game 7.
>
>Pretty much. Part 2 is for all the marbles. BP didn't really
>hurt (I think they should have wiped Okoye, which may have
>stung a bit harder, as it's more believable they write her out
>than BP, though not really because BILLION DOLLARS) but Pete
>did, even though I know he's not dead for long. I think the
>deaths work in the moment for just about everyone, but then
>fade for comic and MCU junkies. For everyone else, they still
>stick. Listening to the people that leave the theater, you can
>tell
>
>While I posted this over in GD, if I had to pare down the
>movies to see for someone that has never seen a MCU movie to
>get who's who and what's going on, I'd say:
>
>Avengers 1 (introduces the team as a whole)
>Avengers 2 (introduces Vision, more info on Infinity Stones)
>GOTG 1 (introduces the Guardians, more Infinity Stone info,
>more Thanos)
>Civil War (Bucky, Black Panther, Spidey, why they broke up)
>Ragnarok (Doc Strange cameo, where have Hulk & Thor been, sets
>the start of IW)
>
>as RJCC said, you CAN go in cold and figure out who does what
>on some level, watching these 5 sets the table for 95% of who
>and what you're looking at. At worst, you could see IW all by
>itself and still have a better idea on what's going on with
>30+ characters than you could with Justice League