Any way to put a simple debounce in this script?

You can use tables to identify if the target player was damaged or not.

local tool = script.Parent.Parent --your tool
local toolActive = false
local damage = 1
local duration = 2
local damagedChars = {}

local function checkIfDamaged(x)
	for index, value in pairs(damagedChars) do
		if value == x then return true end
	end
	return false
end

local function onTouched(hit)
	if not toolActive then do return end end
	local Humanoid = hit.Parent:FindFirstChildOfClass("Humanoid")
	if Humanoid and not checkIfDamaged(Humanoid.Parent.Name) then
		Humanoid:TakeDamage(damage)
		table.insert(damagedChars, Humanoid.Parent.Name)
	end
end

local function onActivated()
	if toolActive then do return end end
	toolActive = true; wait(duration); toolActive = false
	damagedChars = {}
end

script.Parent.Touched:Connect(onTouched)
tool.Activated:Connect(onActivated)