What got me most about Alita, and a major reason why critics are trying to kill it, is that the movie lets Alita be a girl.
She's not perfect, she's awkward, she's goofy, she moons over a boy, she gets emotional, and she still needs a bit of guidance. Contrariwise, you can tell she was at one time a hardcore space soldier and her little flashbacks make sense.
This makes her arguably more human.
Contrast to "Captain Marvel" where some rando girl who looks plain comes out of nowhere, is better than everyone, and is supposed to kill Thanos because the future is female

