jp:
The secret of good world-building is to have the characters take their world for granted and to write for people in that world. I call it the John Campbell dictum, as he told his writers to do that. I find to do this, one simply models writers who are writing in our world but in sub-universe of it that their readers might not know. For example, "The Women's Murder Club." Maxine Petrine goes into detail about San Francisco but has it revealed by the characters navigating around the city. We find the methodology and the hierarchy of the police force by Lindsey navigating it. In this novel, the reader is assumed to have heard of the Silver Wheel, but no details are provided and they can guess it's a powerful witch's society by use of terms like 'nun,' 'sorcery,' and 'Don't mess with the Silver Wheel.' Offworlder is a play on outlander, or foreigner, to refer to aliens. The Marines are modeled after the United States Marines (semper fi) although obviously globalist.
No long descriptions like Gormenghast. And as to long introductions being accepted by fantasy readers, I rest my case. 100-page introduction. The Lord of the Rings? Hey, it turned into a book in its own right--the Hobbit.
Other writers, e.g., Fritz Leiber, jump right into Lankmahr, but from context, you know it's in the desert. You know there are Viking-like Northerners from Fafred.
I think that, yes, if you find that the prologue doesn't really play a part in the hero's story, then it's best to drop it. Although, again from "The Women's Murder Club," one story had an incident at the beginning of the book which played no role at all, except that after the main plot was done, there was a tie-in, pretty artificial. I suspect James Patterson gave it to Maxine as a Writing Prompt, it worked but left a big question that needed to be tied in. Whatever gets the creative daemon off her butt.
Oh, and Merriam-Webster defines 'conflictual' as the adjective form of conflict and 'instinctual' as the adjective form of instinct. 'Instinctually' is the adverb form.
You are right that all novels, at least (literature is a bit broad and I'm sure there are counter-examples) are supposed to revolve around conflict, which makes them conflictual. My point was that the first chapters met this criterion but only pointed in the direction of the main conflict, which some "How to Write Good" authors say should be in the first five pages. Again, not hard and fast, as Conrad didn't start his story conflictually (adverb modifying 'start') until page 10.
Thanks, JP. After all this input, I think I will leave the prologue in, more or less as it is, as it only seems to have been confusing to one reader. I think even that reader went on to find out what the heck was going on--which is the point of a "teaser" prologue.