Screen protector

What would be the purpose of a screen protector on a non-touch screen?

I would not place anything between the keys and the display. I would not adhere anything to the screen.

Do not use palm rest or keycap covers on a Mac notebook with a Retina display - Apple Support

What I can say is that Screen protector is unnecessary.

About cleaning your Mac notebook's screen:

https://support.apple.com/guide/mac-help/clean-your-computer-screen-mchlp2657/mac