This is a mistake I see made often in mecha media where the player character is sort of at best along for the ride and at worst a damsel in distress. This is a result of the fact that the agency of the player character is only expressed in gameplay, and that gameplay offers no other way to win or progress besides “defeat the enemy.”
Why not have the player character enact their own agency in cutscenes? For example, when the mysterious cyclops steals the generators at the dam, maybe the player character could shoot back at him or shoot down one of his drones. Maybe at the end of the oil rig mission where another character steals your kill, the player character takes a bullet for them.
This is a very simple way to improve the player’s relationship with their character without adding anything like backstory or a visual representation.