https://www.cnet.com/news/captain-marvel-concerns-addressed/

Part of the reason Captain Marvel is underdeveloped is because she doesn't actually have a backstory. Where would she even get a personality from? By the end of the film, she seems to have only regained scattered memories and glimpses of her life as Carol Danvers.

The only thing Captain Marvel really remembers is six years of brainwashing by the Kree. That's literally it. Six years of brainwashing and the few days worth of events on Earth that happen during the film. And to her credit, she does establish at least three meaningful connections in that short timeframe, with Nick Fury, Maria Rambeau and Maria's daughter Monica.