We've known that Captain Marvel is the universe's first superhero, but it seems there is more that connects her to the Avengers than just being to the party a bit earlier than the rest.
Marvel's Japanese website holds a few key details, including the year that Captain Marvel takes place, but it also features an interesting line in regards to her effect on the Avengers. The first few lines of text on the page translated reads "Draw the beginning of the hero who holds the key to the "Avengers" birth" Another line reads "The beginning of the hero, which triggered the birth of the Avengers, is now revealed" (via Cosmic Book News).
Now, you could read this as just 'Oh, Nick Fury saw her and figured he should make a full team of Captain Marvels'. You might be right too, but it's that reference to the "key" that interests us most. What happens in Captain Marvel that he doesn't simply go find another hero to take her place but of a team? Perhaps that "key" is the fact that he tries to call her at other times, but the device for some reason doesn't work, or she can't reach Earth in time. If that's the case, then it would make sense that he would want multiple heroes available in case one can't answer the call.
Of course, it could also mean something completely different, but we'll just have to wait and see. We've got plenty of other questions too, like if her origin here will mirror that of The Life of Captain Marvel's recent revelations and just who Jude Law is playing, and hopefully, some of those will be answered in a second trailer.
The Captain Marvel film follows Carol Danvers as she becomes one of the universe's most powerful heroes when Earth is caught in the middle of a galactic war between two alien races. Set in the 1990s, Captain Marvel is an all-new adventure from a previously unseen period in the history of the Marvel Cinematic Universe.
Captain Marvel stars Academy Award® winner Brie Larson (Carol Danvers/Captain Marvel), Samuel L. Jackson (Nick Fury), Ben Mendelsohn, Djimon Hounsou (Korath), Lee Pace (Ronan), Lashana Lynch, Gemma Chan (Minn-Erva), Algenis Perez Soto, Rune Temte, McKenna Grace, Kenneth Mitchell (Joseph Danvers), with Clark Gregg (Phil Coulson), and Jude Law (Marv-Vell).
Captain Marvel launches on March 8, 2019, followed by the fourth Avengers movie on May 3, 2019, and Spider-Man: Far From Home on July 5, 2019.