Getting user input without a tool?

I am currently working on a feature where you can click on certain objects and interact with them in different ways (this is why I have many variables set up, and are not being used). I have first started making interaction with an enemy possible (through setting a combat variable to true and making selection box to red, though I hope to expand it later). When testing this script, scrolling over an NPC will not allow you to see a selectionbox, and clicking it will do nothing, it also shows no errors. I would GREATLY appreciate it if you could figure out what is wrong with the following code:

-- Setting all variables
local player = game.Players.LocalPlayer
local character = player.Character
if not character or character.Parent == nil then
    character = player.CharacterAdded:wait()
end
local charpos = character.Torso.Position
local mouse = player:GetMouse()
local selection = Instance.new("SelectionBox", player.PlayerGui)
selection.Color = BrickColor.new("Medium stone grey")
local combat = script.combat
local talking = script.talking
local reading = script.reading
local questing = script.questing

--check target and make variables when mouse moves
mouse.Move:connect(function()
    local target = mouse.Target
    local hum = target.Parent:FindFirstChild("Humanoid")
    local hrp = target.Parent:FindFirstChild("HumanoidRootPart")
    local enemy = target.Parent:FindFirstChild("enemy")
    local friend = target.Parent:FindFirstChild("friendly")
    local quest = target.Parent:FindFirstChild("quest")
    local book = target.Parent:FindFirstChild("book")
    --check if the target is an npc and not a player
    if target.Parent:IsA("Model") and hum ~= nil and hrp ~= nil then
        selection.Adornee = target.Parent
        -- if the target has the enemy value in it
        if target.Parent.enemy == true then
            --and the player clicks on target
            mouse.Button1Down:connect(function()
                --and the player is close enough
                local targetpos = target.Parent.Torso.Position
                if player:DistanceFromCharacter(targetpos) < 40 then
                    --set combat equal to true, and make the selectionbox red
                    combat.Value = true
                    selection.Ardornee = target.Parent
                    selection.Color = BrickColor.new("Bright red")
                end
            end)
        end
    end
end)

Thank you for reading :)