Data Store stats script is not saving?

Good day, Scripting Helpers. I'm a bit unaware of all the new Roblox features so until recently, I did not know of Data Store saving so I used Data Persistence instead. However, because of Data Persistence issues, I decided on using Data Store instead. I watched a tutorial about how to apply Data Store saving on a stats/leaderstats script and tried to use it for my own stats script. For some reason though, my stats don't save at all. I would really appreciate if someone could explain to me what did I do wrong.

Stats script

local DataStore = game:GetService("DataStoreService"):GetDataStore("PrimpyGameData")

-- The first two functions are most likely irrelevant to my issue.
function onXPChanged(player, XP, level)
    if XP.Value>=level.Value * 40 then
        XP.Value = XP.Value - level.Value * 40
        level.Value = level.Value + 1
        hp.Value = true 
 -- I removed this value (hp) from THIS script because it isn't relevant. It exists though.
    end
end

function onLevelUp(player, XP, level)
    if level.Value>=100 then
    XP.Value = 0
    level.Value = 100
end
end

function onPlayerEntered(newPlayer)

    local stats = Instance.new("IntValue", newPlayer)
    stats.Name = "stats"

    local xp = Instance.new("IntValue", stats)
    xp.Name = "XP"
    xp.Value = 0

    local level = Instance.new("IntValue", stats)
    level.Name = "Level"
    level.Value = 1

 -- Lots of other values similar to level and xp go here. I tested only for level and xp though.


    local key = "player-"..newPlayer.userId
    local savedValues = DataStore:GetAsync(key)
    if savedValues then
        xp.Value = savedValues[1]
        level.Value = savedValues[2]
 -- A bit off-topic but if I add more stats/values, do I just increase the number of
 -- savedValues? Like, savedValues[3], savedValues[4] and so on?
    else 
        local valuesToSave = {xp.Value, level.Value}
        DataStore:SetAsync(key, valuesToSave)
    end

 -- Again, below is most likely irrelevant.
    xp.Changed:connect(function() onXPChanged(newPlayer, xp, level) end)
    level.Changed:connect(function() onLevelUp(newPlayer, xp, level) end)

    newPlayer.Changed:connect(function (property)
        if (property == "Character") then
            onPlayerRespawned(newPlayer)
        end
    end)
end

game.Players.ChildAdded:connect(onPlayerEntered)

Stats saving on player leaving script

local DataStore = game:GetService("DataStoreService"):GetDataStore("PAStats")

game.Players.PlayerRemoving:connect(function(player)

    local key = "player-"..player.userId

    local valuesToSave = {player.stats.Level.Value, player.stats.XP.Value}
    DataStore:SetAsync(key, valuesToSave)
end)

Thank you so much for reading, any kind of answers are appreciated. Have a great day '~'