My Exp/leveling scripts are not working... Could someone look over them please?

Leaderstats (ServerScriptService)

game.Players.PlayerAdded:Connect(function(Player) 
	local Leaderstats = Instance.new("Folder", Player) 
	Leaderstats.Name = "Leaderstats" 
	local Level = Instance.new("IntValue", Leaderstats) 
	Level.Name = "LevelLable" 
	Level.Value = 0 
	local Exp = Instance.new("IntValue", Leaderstats) 
	Exp.Name = "ExpLable" 
	Exp.Value = 0 
	if Player.Character and Player.Character:WaitForChild("Humanoid") then
		Player.Character.Humanoid.MaxHealth = 100 + Level.Value*10
	end
	Level.Changed:Connect(function(value)
    if Player.Character and Player.Character:FindFirstChild("Humanoid") then
		Player.Character.Humanoid.MaxHealth = 100 + Level.Value*10
		end
	end)
	Player.CharacterAdded:Connect(function(character)
		character:WaitForChild("Humanoid").MaxHealth = 100 + Level.Value*10
		Player.Character.Humanoid.Health = Player.Character.Humanoid.MaxHealth
	end)
end)

Character script

local exp = script.Parent.Config.XP.Value

local Humanoid = script.Parent.Humanoid
function PwntX_X() 
local tag = Humanoid:findFirstChild("creator") 
	if tag ~= nil then 
		if tag.Value ~= nil then 
local Leaderstats = tag.Value:FindFirstChild("Leaderstats") 
			if Leaderstats ~= nil then 
Leaderstats.XP.Value = Leaderstats.XP.Value + exp
wait(0.1) 
script:remove()
			end 
		end 
	end 
end 
Humanoid.Died:connect(PwntX_X) 

If you need anything else let me know... Thanks in advance...

This should be very simple. In the tool the player uses to kills the NPC you need to check if the NPC is an NPC and that it is dead and then you need to give the EXP accordingly. I'm not 100% if you can check if the NPC died by a player but you could try seeing if the parent of the tool (assuming the tool killed it) is a character and then use :GetPlayerFromCharacter() to access the player (assuming the exp is stored in the player somewhere).