Thanks for the comment ^_^
Yeah, the way to fix the gun clipping is by creating a second camera that only sees the gun and rendering it on top of the screen as an overlay. I can give you additional details if you want, but you can find this exact solution on YouTube. It feels hacky, but it's technically the correct solution as you would do a similar thing if you were working with low level logic of OpenGL or DirectX anyway: rendering into a separate texture and overlaying. :)
And yeah, you're probably right, I wanted to avoid adding health bars for enemies so it doesn't feel too game-y and clutter the view. But I definitely need to add something to indicate the damage. Currently I'm thinking of at least adding a little indicator of how much damage was done, so it's clear that the enemies are indeed getting damaged :)
once again, thanks a lot for trying it out!