Hey, I checked your prototype, gotta say there is not much to check out but I do have some suggestions, first of all your characters and animations are amazing, specially for someone new to blender, of course it needs some work here and there but it's a solid character design.
I mention a lot in the video but I can drop a quick list here:
-Add some music and sound effects, even if generic they help a lot with the experience.
-Lock the mouse in the screen, i helps with aiming and general game control
-Maybe don't let the player move the camera in the main menu.
-Jumping is fun.
-Maybe an introduction explaining the story at the beginning of the game
Best of luck in your gamedev journey!