Captain Marvel will formally debut in the Marvel Cinematic Universe with her own film this Friday. She is also expected to join the Avengers in their war against the genocidal demigod Thanos in Avengers: Endgame.
Captain Marvel is important not just because she is MCU’s first female lead, but also due to her importance in the Thanos conflict and beyond.
Her real name is Carol Danvers and before she became Captain Marvel, she was a US Air Force pilot, who found herself on a planet under the control of the extraterrestrial Kree empire. Her DNA was fused with that of the Kree DNA (in comics due to an accident but the film might change that), and she became a powerful being with superpowers. She also became a member of the Starforce, a Kree military team.
Sometime in the 1990s, she crashed back to earth and met Nick Fury. Together they fended off the invasion by the Skrulls, a bellicose race of alien shapeshifters. But when the Avengers was formed, Carol was not invited to be a part of it by Fury. She did not come when Loki and the Chitauri invaded the earth, and also when Ultron went berserk in Avengers: Age of Ultron.
But when Fury became aware of Thanos’ snap, he remembered to contact her through a pager-like device before apparently dying. So why did he remember her only when Thanos invaded and not before? If you remember, the Avengers were almost overpowered against the endless numbers of the Chitauri before somebody remembered to plug the wormhole.
We will presumably know that in the movie, but Fury contacting her underlines how important Captain Marvel is to the future of the MCU. Due to her adventures with the different races of the universe and her awareness about universal level threats makes her uniquely equipped to deal with somebody like Thanos. She likely knows more about him than any other character, though it remains to be seen where was she all this time.
We already know that she is super-strong, stronger than Hulk and even Thor, who almost killed Thanos in Infinity War. Her knowledge of the forces operating in the universe and her superpowers make her very crucial to the Avengers’ final fight against Thanos and their plan to bring the people who died as a result of Thanos’ snap.
Captain Marvel will also evidently lead the future generation of the Avengers, which makes her an important part of the MCU.
Captain Marvel releases on March 8.