So the output isn't detecting the player touching the part sand. Anyone know why?

Sand = game.Workspace:WaitForChild("Sand")
local TouchableParts = {}
local tableposition = 1

for i, v in pairs (Sand:GetChildren()) do
    if v:IsA("BasePart") then
        table.insert(TouchableParts, tableposition, v)
        tableposition = tableposition + 1
    end
end



for i, v in pairs (Sand:GetChildren()) do
    if v:IsA("BasePart") then
        table.insert(TouchableParts, tableposition, v)
        tableposition = tableposition + 1
    end
    wait()
end


for i, v in pairs (TouchableParts) do
    v.Touched:Connect(function(hit)
        local player = game.Players:GetPlayerFromCharacter(hit.Parent)
        if player then
           game.ReplicatedStorage.GravityController.disabled = false
		end
    end)
end

You don't need a for loop in this case

I made a simple script for you to follow.

Sand = game.Workspace:WaitForChild("Sand")
 script.Parent.Touched:Connect(function(hit)
	if hit.Parent:FindFirstChild("Humanoid") then
		-- do whatever you want here

	end
end)