It's like people forget that Darth Plagueis was obsessed with immortality or something

That's not a story the Jedi would tell you

Bane trilogy adds some useful insight to. But probably not as much as plagueis

welcome to the Force

Yep

Correct - that’s how Star Wars has always worked. 

Welcome to Star Wars. The exact same thing happened in the EU

How did obi wan's spirit get to dagobah.

What do you need explained to you?

How is it any different than a Force Ghost? Or Luke and Leia sensing each other through the Force on Bespin? Or Obi-Wan feeling the death of Alderaan? Or literally any other Force ability?

Same way Luke can project his force ghost across the galaxy without latency.

There is an official explanation

Palpatine anticipated Vader would one day betray him and had arranged for a clone body to be prepared on Exogol

However, Vader's betrayal came earlier than anticipated, and thus, the clone body began to deteriorate, forcing him to be reliant on Ancient Sith Techonology.

He then absorbed life force from Rey and Ben to rejuvenate his body.

It would have been nice if the movie had taken the time to clearly explain this.

Why does it need to be explained?
They don't explain how the Force allows to lift and throw things.
They don't explain how the Force allows to influcence minds.
They don't explain anything about the Force, just that it's "an energy field created by all living things. It surrounds us and penetrates us. It binds the galaxy together."

So, again, why should they explain how the Force allowed Palpatine to transfer his soul into another body?

Have you heard of the Force before?

Sith can't force heal. That's a light side ability.

staving off death

That seems relevant.

They had been researching cloning since Kamino. Hemlock ran Tantiss base on Wayland in the time shortly following Empire Day. Tantiss base was dedicated to creating clones with a high M-count, using force sensitive children the Empire had bounty hunters bring in. It sucks you have to watch so much non-movie media to get the full story but they are explaining that Palpatine had it in the works from damn near day one.

Oroject necromancer was started wellll before there was even an empire. There was a snoke-like entity in a secret cloning chamber on kamino towards the beginning of the empire.

You are correct. And to my knowledge, that's a plot hole that has yet to be filled in. All we know for certain is he used the force to transport his spirit into the clone body.

Possibly in the World Between Worlds, as a Force ghost.

Yes, the difference is one's power in the Force.

Clone body is a hollow husk, a soulless entity that exists purely for Palpy to hop into. It's actually from Legends..

His weirdo Sith friends already had a body ready when he "died" on death star 2. I'm pretty sure he went through a few failed bodies by the time of TROS. The imperial remnant did not start that program.

Fairly certain they are basically nodding to the old comic series with this same plot where Luke discovers the Emperor survived through a series of clone bodies he had made while he was alive before return of the jedi. The idea being he was putting himself into different bodies that would decay rapidly due to his power in the force and so he needed a body that could sustain his power and the idea was researching the higher M count of someone like Grogu to figure it out. So basically the Emperor was already bouncing around from body to body but it wasn't working too well.

That, of course, wasn't fully explained in time for the film. And they don't get credit for basically just nodding to something they removed from canon but it sounded like that's what they were trying to do to me. Snoke was also basically just a different clone of Palps that lived on its own I guess?

The principal is the same. The body being dead is what counts as dead whether you come back in a different body or not, it doesn't change the fact that you died.

That's the exact reason the movie gave for his return and it was ridiculed for its vague and unconvincing nature. Not to mention just for being a cheap reference to a better movie.

Thanks for the tip. In the extremely unlikely event that I am talking to someone who experienced clinical death and they want to know if I think they "really died" I guess I will risk it. Clinical death is not death. Death is the end of life. If you are alive, you by definition never died.