How do you make an identifier without changing model name?

Im trying to make an enemy for my RPG but im having a hardtime setting up the damage i want to make it so that it can decipher whats a player and whats an enemy and whats a Player so that the sword doesnt do damage to any humanoid

function isPlayer(character) --character model
	if game.Players:GetPlayerFromCharacter(character) then
		return true
	end
	return false
end

That should be helpful to you