The entire point of Metroid is that you are Samus in the lonesome hostility of an alien world. About the best representation of a Metroid movie I can imagine would be aping the film Dredd, where Samus is presented as an already-established badass who wades into a hostile environment, barely talks, kills Space Pirates, refuses to elaborate, and leaves. Only vague hints at her backstory should be presented. Maybe give her a partner like U-Mos who is connected to the location to explain small tidbits about the alien planet.
They would never do that, they would make Samus a boss bitch who marvelsnarks at all of her enemies with the Metroid Larva as the cute little creature for toddlers to coo and squeal at every time it does something cute.
There shouldn't be a Metroid movie. Ruin Starfox and its incredible legacy of one good game and a million furries instead.