Aiming is a mess. You should at least make it so the mouse gets captured at the same height your bullets are being spawned at, otherwise the aiming is not going to be accurate whatsoever.
The camera system is not optimal either; it's too zoomed in, and lagging behind the player so much means if you're running towards any direction that's the direction you see less towards, which is bad. Placing the camera halfway between the player and the cursor is probably the easiest solution, otherwise just keep camera fixed on the player.