Correct! The Cradle is the default / canon setting of the game, but what the Cradle looks like, how it operates, and what its history is are completely up to the table. You also don't need to use the term "Cradle" to describe your world if you don't want to. The full game will include more detailed setting information about various versions of the Cradle, including the one featured in the GODKILLER: First Blood podcast series!
Editing to add that the full game will also include guidance, rules, and advice for homebrewing your very own Cradle.