There is no Culture rules container in any way, and Backgrounds are not cultures.
We have been over this.
The 2024 rules, and the shallow extent that any kind of guidance is provided, does nothing from what I can see to aid or teach, world building at all.
Are the Gods detailed? What of their faiths? Are there actual cultural differences outlined, and how are those mechanically represented if every culture has the same Charlatan, Farmer, and Hermit.
Those are your Backgrounds. Capital B. That is a Rules Container.
Tell me, as a 'I just got my first D&D Book, 2024 PHB' who is Gruumsh, and what does he believe and ask of his followers?
Go to your Index. You'll find 'background' on page 378, first page of the index.
You will not find culture. Its not a thing, you are making it up as you have before.