Why cant you ask if something is not inside of a table.. im frustrated?

You cannot do that with numeric indices. However, you can do that with string indices. A simple example:

local array = {}
array["hello"] = true
print(not array["hello"])

Side note for future reference:

local array = {}
array["hello"] = true
-- is the same in Lua as
array.hello = true

Putting this all together, we can create a debounce with player names as the indices. I hope this helps. Have a great day scripting!

Edit with example:

local players = game:GetService("Players") -- the recommended way to get any service, including players
script.Parent.Touched:Connect(function(hit)
	if hit.Parent:FindFirstChild("Humanoid") then
		local player = players:GetPlayerFromCharacter(hit.Parent) -- a useful method to get the player
		if player then
			local specialKey = tostring(player.UserId) -- I prefer the userid
			if not playerDebounceList[specialKey] then -- checking for debounce
				playerDebounceList[specialKey] = true -- placing them in the table for debounce
				-- do your code here
			else	
				wait(1) -- waiting and then removing them from the list
				playerDebounceList[specialKey] = nil
			end
		end
	end
end

The main issue with your code is that table.insert places the item at a numeric index at the end of the table if no index is specified. Also, when you did your checking, you were checking for the player's name as an index when it was really a value in the table.