attempt to index local 'left' (a nil value) works if i use humanoid but not a limb?

local ReplicatedStorage = game:GetService("ReplicatedStorage") 
local createPartRequest = ReplicatedStorage:WaitForChild("puncher")
local finna = ReplicatedStorage:WaitForChild("damage")
local player =  game.Players.LocalPlayer
local char = player.Character
local hum  = char:WaitForChild('Humanoid') 
local  left = hum:FindFirstChild("LeftHand")


function onKeyPress(inputObject, gameProcessedEvent)
    if inputObject.KeyCode == Enum.KeyCode.E then

local newPart = createPartRequest:InvokeServer()




    end
    end

game:GetService("UserInputService").InputBegan:connect(onKeyPress)

left.Touched:Connect(function(hits)
    if hits.Parent:FindFirstChild('Humanoid') then


    local target = hits.Parent:FindFirstChild('Humanoid')
    local newthing = finna:InvokeServer(target)


    end
end)

dunno whats wrong but it works if i use humanoid instead of the left hand and i kinda wanna use the left hand but idk how to fix