for pointers on how to compress a story. Maybe if it's bad, I should watch it for pointers on how not to compress a story.

I have a story I want to write (sci-fi) featuring a medieval civilization that lives alongside and dominates another civilization that (at the beginning of the story) doesn't even have language and is arguably on the cusp of sapience, which muddles the morality for the dominant civilization for whether their dominance is properly described as 'domestication' or 'slavery'. Fraught topic.

A third, not-present, civilization (sci-fi advanced almost magic-level tech) has also left behind evidence of its existences, in various forms but in particular in the form of immobile machines that kill any living thing as large as any member of the primitive society and most members of the more advanced society (who are much smaller than the primitives) and both of those societies interpret this as "The gods are murderous a-holes who want us all dead."

By the end of the story (many many generations after the beginning) the primitives will be language-users and simple machine builders and the murderous intentions of the very advanced are made clear and the two existing civilizations will have resolved their conflict one way or the other.

The things that make me not want to write the story are:

I've never really written even a good short story before.

The racial allegory of the two civilizations would be very tough to navigate. I would be writing about two different species that evolved separately (there are physical/technological reasons why the first to evolve can't really wipe out the second) and their shared ancestor would be as far back as something like the shared ancestor for humans and pandas, but it's likely any publisher would balk at the implications that could be assumed. I can't write the more advanced of the two civilizations as more enlightened (more than humans currently are, say) because that removes any of the story's conflict and realistically the more advanced civilization (if I make them that morally advanced) would probably have solved the mystery of why the 'gods' want everyone dead long before the evolution of the second civilization.

The POV of the barely-sapient characters would be tough to write. Maybe I need to read Clan of the Cave Bear? Or re-read White Fang? Parts of that book are told from the POV of dogs in a way that makes them 'almost human' and gives them about the level of intelligence/understanding I would want my characters to have, at least at first.

Eh... the whole thing is pretty daunting but it's been kicking around in my brain for about 15 years and the driving technology (of the 'gods' ) that causes the rest of the story to happen is interesting to me and would make a good reveal. I mean, a typical sci-fi story would say 'these are weapons of war that wiped out their creators and outlived them' but that's cliché and I've got a better reason why they exist AND my reason explains why their creators built them to last on a geologic/evolutionary timescale.

I have another storytelling gimmick in mind that I think would be very cool that I've never seen done before and to describe it would be to ruin it but suffice it to say the gimmick itself also increases the difficulty of the project.

Maybe I need to tell it like the 'Bolo' tank sci-fi stories. Instead of a continuous narrative, just a collection of short stories that gradually tells the epic tale of the rise of the Concordiat of Man and their war of extermination against the Melconians. That probably is the only way to tell my story, really. It definitely removes the possibility that I could employ the previously-described storytelling gimmick, though.