How do i make the server fire the function?

i just started attempting server remotes so idk whats wrong but what im trying to do is when i holddown t then the player i click on will die

server script:

local Plr = game:GetService("Players"):WaitForChild("world_kiIIer")



local remote = game:GetService("ReplicatedStorage"):WaitForChild("killplayer")

local Mouse = Plr:GetMouse()





remote.OnServerEvent:connect(function(world_kiIIer)

world_kiIIer:GetMouse().Button1Down:connect(function()

if not game:GetService("UserInputService"):IsKeyDown(Enum.KeyCode.T) then return end

if not Mouse.Target then return end

Mouse.Target.Parent.Humanoid.Health = 0

end)

end)

local script:

local repstore = game.ReplicatedStorage

local remote = repstore:WaitForChild("killplayer")

local player = game.Players:WaitForChild("world_kiIIer")



remote:FireServer(player)

my error: ServerScriptService.Script:8: attempt to index a nil value

if someone knows what im doing wrong please tell me, this is my first attempt on a serverscriptservice script