I’ve been reading Marvel comics since I was in Elementary School and I know nothing about the Eternals
So does anyone know what comics I should read to get up to date? The Essential Eternals reading
You don't. They were a Kirby passion project, and as a writer, Kirby was a great artist.
They were meant to be the big cosmic explanation of where all the powers and backstories and THINGS came from.
This was after Kirby had already tried to do the same thing at DC with Darkseid and the New Gods and all those titles got cancelled because no one cared about those characters except for Darkseid.
In both cases, after Kirby stopped working on them, no one knew what to do with them, so they retconned and reworked, and retconned and reworked, and retconned and reworked, and nothing has stuck or been definitive.
Similarly, no one has ever really gotten the Inhumans to work except as antagonists to the fantastic four, despite having a couple strong iconic characters there's never been anything THERE for anyone to make anything out of, they've just been around so long that its assumed there must be SOMETHING to them..
So they're characters that exist but you're not missing anything.
It's pretty likely the movie will be the best version we've gotten of them, if for no other reason than it gets a clean slate and isn't trying to explain 50 years of comics continuity.
Moviebob did a LONG summary on all their… stuff, but i'm loathe to link to him since it came out he's kind of awful on twitter.