Character and arms following player's mouse?

local tool = script.Parent.Parent
local service = game:GetService("RunService") --get  run time servise

local success = false

local player = game:GetService("Players").LocalPlayer --get the current player
local character = player.Character or player.CharacterAdded:wait() --get character
local humanoid = character:WaitForChild("Humanoid") --get humanoid

local camera = game.Workspace.CurrentCamera --player camera
local mouse = player:GetMouse() --player mouse

local offset, magnitude, vector3, cFrame, direcction = nil --varibles to make calculations
local shoulder, arm, torso, body, neck = nil --variables to hold body parts
local defaultNeckCO, defaultShoulderCO = nil --variables to hold the defauld posicion of the body parts
local animate = nil --variable to hold the function of the animation

local shoulderPositionC0, shoulderCFramePositionC1 = nil --variables to extrack some data from the body parts
local turnAngle = CFrame.fromEulerAnglesXYZ(math.pi/2, 0, 0) --constant, used later on to make calculations
local rightangle = CFrame.fromEulerAnglesXYZ(0, 0, math.pi) --constant, used later on to make calculations

local unequipListener --listener to disconect the unequip function

--get offset
function updateOffset()
	offset = (body.Position.y - mouse.Hit.p.y) / 100
	magnitude = (body.Position - mouse.Hit.p).magnitude / 80
	return offset/magnitude
end

--get vector3 of direccion
function updateBodyRotation()
	
	if (camera.Focus.p - camera.CoordinateFrame.p).magnitude > 1 then
		--stop the defauld rotation
		humanoid.AutoRotate = false
		
		--get the rotation vector3
		vector3 = Vector3.new(mouse.Hit.p.x, body.Position.y, mouse.Hit.p.z)
		
		--create the cframe with the same posicion of the body and the new rotation
		cFrame = CFrame.new(body.Position, vector3)
		
		--updating the body rotation
		body.CFrame = cFrame
	else
		--get the defauld rotation
		humanoid.AutoRotate = true
	end
	
end

--function to animate the humanoid R15
function animateR15()
	--update neck
	offset = updateOffset()
	neck.C0 = defaultNeckCO * CFrame.fromEulerAnglesXYZ(-offset, 0, 0)
	
	--update arm
	vector3 = (torso.CFrame * CFrame.new(shoulderPositionC0)).p + Vector3.new(0, -0.25,0) --offset position
	direcction = (vector3 - mouse.Hit.p).unit 
	arm.CFrame = CFrame.new(vector3, vector3 + direcction) * turnAngle * shoulderCFramePositionC1 * rightangle 
	
	--NOTE: the following changes update the arm in a lesser accurate way, but it's faster,
	--to change the faster way, must comments the previous update arm (previus 3 code lines),
	--and add the following code line in the "getBodyParts()" in the R15 side
	--defaultShoulderCO  = CFrame.new(1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1)
	--then uncomment the following code line
	--shoulder.C0 = defaultShoulderCO * CFrame.fromEulerAnglesXYZ(-offset, 0, 0)
	--at last, the shoulder.C0 take some changes in the animation,
	--the defauld posicion have to by reset in defauld on "stopAllFunctions()", with the following code line:
	--shoulder.C0 = defaultShoulderCO
end

--function to animate the humanoid R6
function animateR6()
	--getting the offset
	offset = updateOffset()
	
	--update neck and arm, NOTE: this is almost the only variation between R6 nd R15,
	--and basically it's where is going to be the offset
	neck.C0 = defaultNeckCO * CFrame.fromEulerAnglesXYZ(offset, 0, 0)
	shoulder.C0 = defaultShoulderCO * CFrame.fromEulerAnglesXYZ(0, 0, -offset)
end

--function to get parts of the body depending on the humanoid
function getBodyParts()
	
	--same body in both humanoids types
	body = character.HumanoidRootPart
	
	--bifurcate between diferents humanoids to get part of the body
	if humanoid.RigType == Enum.HumanoidRigType.R15 then
		--R15
		
		--getting body parts
		shoulder = character.RightUpperArm.RightShoulder
		arm = character.RightUpperArm
		neck = character.Head.Neck
		torso = character.UpperTorso
		
		--deatach the arm
		arm.Anchored = true
		shoulder.Part1 = nil
		
		--setting animation
		animate = animateR15
		
		--Note: those CFrame are the defauld position of each motor6d
		defaultNeckCO = CFrame.new(0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1)
		shoulderCFramePositionC1 = CFrame.new(shoulder.C1.p)
		shoulderPositionC0 = shoulder.C0.p
	else
		--R6
		
		--getting body parts
		shoulder = character.Torso["Right Shoulder"]
		arm = character["Right Arm"] 
		neck = character.Torso.Neck
		
		--setting animation
		animate = animateR6
		
		--Note: those CFrame are the defauld position of each motor6d
		defaultNeckCO = CFrame.new(0, 1, 0, -1, -0, -0, 0, 0, 1, 0, 1, 0)
		defaultShoulderCO = CFrame.new(1, 0.5, 0, 0, 0, 1, 0, 1, 0, -1, -0, -0)
	end

end


--this function try to stop all function of this script and set defauld values
function stopAllFunctions()
	
	pcall(function()
		--disconect the unequip tool listener
		unequipListener:Disconnect()
	end)
	
	pcall(function()
		--stop the rendering of the animation
		service:UnbindFromRenderStep(script.Name)
	end)
		
	pcall(function()
		--reset defauld position of the neck 
		neck.C0 = defaultNeckCO
	end)
		
	pcall(function()
		--reset the defauld rotation of the body
		humanoid.AutoRotate = true
	end)
	
	pcall(function ()
		if humanoid.RigType == Enum.HumanoidRigType.R15 then
			--R15 
			--atach the arm
			shoulder.Part1 = arm
			arm.Anchored = false
		else
			--R6
			--reset defauld position of the arm 
			shoulder.C0 = defaultShoulderCO
		end
	end)

end

--function to animate the character
function characterFollowTool()

	--try to render the animation
	success = pcall(function()
		--update the Bogy rotation and offset
		updateBodyRotation()
		
		--execute the animation, this function it's diferent depending of the humanoid type
		animate()
	end)
	
	--if the rendering went wrong, 
	if not success then
		stopAllFunctions()
	end
	
end

function onEquip()
	--add listener to the tool to stop all functions when the tool is unequipped  
	unequipListener = tool.Unequipped:connect(stopAllFunctions)

	--getting the parts of the current character
	success = pcall(getBodyParts)
	if not success then
		stopAllFunctions()
	end
	
	--adding the animation in the rendering of the screen
	service:BindToRenderStep(script.Name, Enum.RenderPriority.Input.Value - 1, characterFollowTool)
end

tool.Equipped:connect(onEquip)

There a script i found in toolbox. I dont know how to make the same movement but with left arm. This script only moves head, torso and right arm.