I write as a passion project and for fun with no intention of ever publishing anything so yeah i do mostly worldbuilding
Occassionaly i explore different character ideas but dont stick to them for too long.
But as others have said if you plan to end up with a novel you cant really have a book...
In my world, its meant to mirror the medieval world, so broadly its mostly frowned upon or even criminal. Our continents exist here, so christianity, islam, judaism do aswell, all three are world religions although due to the size of the world none of them make up more than 7% of the world religion.