How do I fix "Humanoid Isn't a valid member of Player"?

Humanoid is apart of the Character, not the Player

We can get the Character by doing player.Character. You can use .Character on any player to get the character. Sometimes the Character hasn't loaded though, so you would wait for the event CharacterAdded to fire. Example,

local player = game.Players.LocalPlayer
local char = player.Character or player.CharacterAdded:wait()
local s = char:WaitForChild("Humanoid")
while wait() do
	script.Parent.Text = s.Parent.Name
end

I also used WaitForChild on the Humanoid, and changed the loop for the wait to be in the while loop to make things smaller.

Good Luck!

If I helped, please don't forget to accept my answer!