static variable

I have searched it and I think I get It but I still have some questions. So I'm following the Survival Shooter Official Tutorial and I came across with a static Score. I know that Static means that through all instances of the class ScoreManager the variable Score will share the same value because player won't have more than one Score so It makes sense. But the enemy has only one health too, so couldn't the variable playerhealth be static too? Also how would be the approach in a multiplayer game?