I have created this code(shown below), it makesa BodyForce and sets it's Parent as the targets humanoid however nothing happens.
local event = game.ReplicatedStorage:WaitForChild("Remotes"):WaitForChild("FlingHandler")
event.OnServerEvent:Connect(function(Player,hit)
local Force = Instance.new("BodyForce")
local Look = Player.Character.HumanoidRootPart.CFrame.LookVector
Force.Force = Look*8000
Force.Parent = hit.Parent.Humanoid
wait(.25)
Force:Destroy()
end)

8 comments
The parent of a BodyForce should be some kind of part, not a humanoid. You should therefore parent it to the HumanoidRootPart which can be found in the character
Force.Parent = hit.Parent.HumanoidRootPart
Still did nothing.
Check if the hit.Parent.HumanoidRootPart is not anchored
it can also be being destroyed very quickly. try to put wait(0.5) or wait(0.7) or more, if solved your problems put [SOLVED] in title
When you hit someone with your hammer it runs this code, which it does, but there are no signs of the Force actually doing anything, but it is Parented to HumanoidRootPart
put the script of fire the event in message, with get the hit.
Getting the hit is a localscript though