Spice is Worm Poop ... If I didn't read that I concluded it ....
Message:The remote planet had the spice which let the space dudes fold the space and live a long time.
As you took the spice it mutated you.
Why else would you not hunt them to extinction? If the worms existed anywhere else, they would have been destroyed before it was discovered what they pooped.
I have not seen this adaptation. Still over loaded for a bit.
The witches DID control everything. Until the one Mu'adib drank the water ... basically ... one of the people with the magic power escaped their clutches. The ritual is not the important part. Basically, one of the people with the ability to foretell the future escaped their order. Perhaps you might call them an immune. The "sight" is the ability to foretell the future. Is that "magic" or just careful study?
The concubine of Leto Atreides decided to have the son Paul when the witches wanted her to have a daughter. She gave the Duke what he wanted. He had "the gift" because he was supposed to be a "she".
The witches wanted to join the two houses with the two children. They had the shit planned out for generations. They were basically growing the messiah.
So now the two houses are in conflict and a danger to the Emperor.
(It describes in the books how the priests go to planets as they develop and seed them with the ideas of their religion.)
Jessica (the concubine) screwed it up.
The War for Dune is devised by the Emperor to keep his Rivals, the Harkonans and the Atriedes fighting. They can't depose him if they are too weak from fighting. (Of course, the Witches know this .... they have set the forces in motion for the Emperor to take that action.)
The later books speak more about the assassins ... if they want you dead, you are dead. Yet, they don't kill for just spite or temporary power. It's long term, cold and calculated.
And, lastly ... not to forget. There are no good sides in Dune. They are all ruthless tyrants. Leto is just a little less of a tyrant than the Baron. The Emperor is equally a sociopath.
Mu'ahdib doesn't use his power for good. Just another tyrant.
There were some missteps in the 1980's Dune but if you tolerate the things that were not done well, it covers the story pretty well. It's a big tale and hard to describe each thing.
Yours,
IronConrad
26-Oct-2021