How can I find a player in the real server?

(sorry if the title is misleading, I couldn't convert it to a question. The original name was "FindFirstChild question")

So I am making a script where I want a person to touch a brick and it falls down on them (already made) and when the brick touches the ground, it will kill the person.

The output shows nothing because I can't see it during a real game and in studio my player is named "Player"

So I did:

 wait(1)
death1 = game.Workspace.Box

 function onTouch(hit)
 	death1.CanCollide = false
	game.Workspace:FindFirstChild("Box")
	if "Box" ~= nil then
		death1.CFrame = CFrame.new(120, 18, -475)
		wait(0.2)
		death1.CFrame = CFrame.new(120, 11, -475)
		wait(0.2)

   local b = game.Workspace.Player:FindFirstChild("Humanoid")
  		if b ~= nil then
  			b.Health = 0
	end
 
 		wait(3)
 		death1.CanCollide = true
		if b.Health == 0 then
			death1.CFrame = CFrame.new(120, 18, -475)
			death1.CanCollide = false

 script.Parent:connect(onTouch)

now this all works fine.

BUT

When I get out of studio and test it, it just falls down and do nothing. I know why it doesn't, because in workspace it doesn't find "Player" because my username isn't player.

So my question is, how would I find a player and kill them if their name isn't "player'?

This would be really nice if I could get it to work.