Why doesn't mouse input work with my custom StarterCharacter?

I'm creating a game where its theme revolves heavily around the custom character I created for my game, but I've run into an issue with it. When I DON'T have the custom character applied(so you just play as your regular ROBLOX avatar instead of the custom one), mouse input works just fine. However, when I apply the custom character mouse input stops working. I've tried many different variations and none of them have worked. The model does have everything a person needs, arms, legs, head, torso, humanoidrootpart, and humanoid.

Some code I've tried:

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()               


local function onMouseClick()
    print("Mouse Click")
end

mouse.Button1Down:Connect(onMouseClick)

The code above works without the model, but with it the code fails to print, but yet returns no error messages

local UIS = game:GetService("UserInputService")

UIS.InputBegan:Connect(function(input, gameProcessed)
    if input.UserInputType == Enum.UserInputType.MouseButton1 then
        print("Mouse Click")
    end
end)

The code above also fails to work with the model and also returns no error messages