Hi there,

So, you would like a script that disables jumping in a part, however, based on your script above, when you set jump to false, the player is still able to jump as that option only can detect if a player is jumping, whereby when the player pressed spacebar, Jump will turn to true before turning back to false. Thus, in order to stop a player from jumping, you should use JumpPower. By default, the player can jump to a JumpPower of 50, So, setting the JumpPower to 0 will force the player to be unable to jump. Additionally, in order to make just a single player do it, you should write your script inside a local script and parent it under StarterPack. Since the StarterPack only loads when the player loads in, the script will only activate when the player joins the game.

If your game is to be not filtering enabled (In experimental mode), server scripts and local scripts will not be able to communicate with each other so I do suggest that you put a remote event such that when on Touch, activate the remote event to the local script.

So here is what your script should look like: I do suggest using filtering enabled to prevent hackers.

1 If you don't have filtering enabled.

Local script:

local detecttouch = game.Workspace.(Part detector's name)

--When Touched
detecttouch.Touched:connect(function(hit)
    --get the humanoid (This is how you find for humanoid with an Touched event)
    humanoid = hit.Parent.FindFirstChild("Humanoid")
    --Check for humanoid (Only found in players, so that other parts which touch this will not activate this script)
    if humanoid then
        humanoid.JumpPower = 0
    end
end

--When Touch ends, allow jumping
detecttouch.TouchEnded:connect(function(hit)
    --Can't delete hit as these are two separate functions
    humanoid = hit.Parent.FindFirstChild("Humanoid")
    --Reset to default
    humanoid.JumpPower = 50
end

2 If you have filtering enabled

Server script:

--Create remote event on Touched to communicate between server and player scripts(client)
local RemoteEvent = instance.new("RemoteEvent)
RemoteEvent.Parent = game.WaitForChild("ReplicatedStorage")
RemoteEvent.Name = "ActivateTouch"

--Create remote event for TouchEnded
local RemoteEvent = instance.new("RemoteEvent)
Touchends.Parent = game.WaitForChild("ReplicatedStorage")
Touchends.Name = "Touchend"

local detecttouch = game.Workspace.(Part detector's name)

--When Touched
detecttouch.Touched:connect(function(hit)
    --get the humanoid (This is how you find for humanoid with an Touched event)
    humanoid = hit.Parent.FindFirstChild("Humanoid")
    --Check for humanoid (Only found in players, so that other parts which touch this will not activate this script)
    if humanoid then
        local player = hit.Parent.GetPlayerFromCharacter()
        RemoteEvent:FireClient(player)
    end
end)

--When Touch ends
detecttouch.TouchEnded:connect(function(hit)
    --Can't delete hit as these are two separate functions
    humanoid = hit.Parent.FindFirstChild("Humanoid")
    local player = hit.Parent.GetPlayerFromCharacter()
    Touchends:FireClient(player)
end)

In localscript:

local remoteEvent = game.ReplicatedStorage:WaitForChild("ActivateTouch")
local Touchends = game.ReplicatedStorage:WaitForChild("Touchend")

--When Touched
remoteEvent.OnClientEvent:connect(function(player)
    player.Character.Humanoid.JumpPower = 0
end)

--When Touchends
Touchends.OnClientEvent:connect(function(player)
    player.Character.Humanoid.JumpPower = 50
end)