their lore sounds pretty retarded

You're not wrong but part of that is due to a lot of retcons happening over the years. Reactivation wasn't a thing for a long time despite it being retconned to have always existed. The purpose of the Eternals has changed numerous times too from planetary protectors to experiment control factors with the importance of the Celestials original creation of the Eternals and Deviants being swapped around a few times.

Another problem with them is that the movie just doesn't really match up at all with the comics, regardless of what retcons are and are not used.

The movies have some vague similarities in terms of the characters but a lot of it is very different. The movies have 10 Eternals, while the comics have 100. Even the 10 in the movie all needed enough time to be introduced and explained while the comics not only still haven't named all 100 they only named some of the significant ones to AXE in the the issue the OP pic is from so it's still an ongoing process there.

Comics Eternals are there to prevent a pot from boiling over that the Celestials left on the hob a million years ago. This is a retcon, however.

Film Eternals are a defense mechanism to ensure an Emergence event occurs which births a new Celestial from a planet. This not only destroys the planet but obviously kills everything living on it which is the main point of conflict in the movie that only really arises in the Third Act. Prior to that the First Act establishes the Eternals as existing to destroy Deviants, Deviants themselves made to wipe out apex predators so lots of life can spread on a planet until the Emergence event is triggered by enough life being present, while the Second Act attempts to solve the murder of one of the Eternals.

It's a significantly divergent story from the comics that beyond the characters involved it's a totally different story. Every other MCU project has at least been more or less on point with the characters except from both Captain Marvel and Ms Marvel of all things. Captain Marvel in the comics is half human/Kree hybrid that should be closer to an Inhuman than an Infinity Stone powered/sort of makeshift Inhuman plank of wood while Ms. Marvel is an Inhuman in the comics yet the MCU appear to be making her a mutant. Everyone else pretty much still follows their comics origin except Scarlet Witch but then she too has had like 4 different origins in the comic by this point due to retcons.