Why does the gravity make this animation break?

All works well, the animation plays. But when it is run the object falls to the ground and not in the air as I had in the animation editor. Why is this, is there a way to prevent this?

This is not a Roblox player rig, but a custom fully working model

--Activators by proo34.
--Used to fire actions in world.
script.Parent.Transparency = 1

--Workspace Requirnments
local Alien = game.Workspace.SnakeTail

print("Activator -" .. script.Parent.Name .. "- is ready for use.")
local Activate = script.Parent.CanActive
local Deactivate = script.Parent.Deactivate

-----------------------------------function-----------------------------------------------

local function PlrHit()
warn("-" .. script.Parent.Purpose.Value .. "- was activated in -" .. game.Name .. "-")
local AlienAnim = Alien.Humanoid:LoadAnimation(Alien.Animation)
AlienAnim:Play()
if destroyfunct == true then
script.Parent:Destroy()
else
print("Repeatable")
end
end

-----------------------------------function-----------------------------------------------

timepertimeout = 0.2 --Time inbetween time outs.
timedout = false --Used in code to let script know if it can be used.
repeatable = false --Set to make a block repeat or run only once.
hitcount = 0
destroyfunct = false
	
if Deactivate.Value == true then
print("Activator -" .. script.Parent.Name .. "- is disabled.")
script.Parent:Destroy()
--Activator Destroyed
else
	
script.Parent.Touched:Connect(function()
if repeatable == true then
print("Im going to repeat")
destroyfunct = false
else
PlrHit()
destroyfunct = true
end
end)
end
 --Full if