Actually this isn’t 100% true, the Animator is being undocked from Humanoid, you should be using the animator class directly now.
Read more here: Deprecating LoadAnimation on Humanoid and AnimationController
As for your issue, you cant play Animations directly, you need to load them into an AnimationTrack before playing it
local Animation = script.Parent.Animation
local AnimationTrack = script.Parent.Humanoid.Animator:LoadAnimation(Animation)
AnimationTrack:Play()