My head-canon is that The Star Wars happens in the same universe as the rest of the main saga, but it happens in a very, very distant future, possibly 500,000 years after the Battle of Endor. Which explains why a lot of things seem so different, while other names and concepts seem so familiar.
Given that names tend to repeat over time, it’s not crazy to assume that other people would be called Leia, or Luke, or Han over time. Just like there are several people called John, or Samuel, even with the same surnames as other people called John and Samuel.
Furthermore, it should also be taken into account that Shmi Skywalker was not the only Skywalker in existence. She had a father, like all normal humans, whose surname must have been Skywalker, too, given that he was her father, indeed. Now, they never explicitly stated that she didn’t have siblings, or that her own father didn’t have siblings. So, the branch of the Skywalker family that generated Anakin and Luke Skywalker might not be the only branch of the Skywalker family in existence. Therefore, it is possible that the Luke Skywalker we see in The Star Wars doesn’t even come from the same branch of the family from which the original Luke Skywalker comes. And even assuming that the Luke Skywalker we see in the comic is a descendant of Anakin and Luke from the movies, it would still make sense in my opinion. Because again, names tend to repeat over time, so it’s not impossible to conceive that, thousands of years after the movies, there could be another Skywalker called Luke.
The same can be said about the reptile version of Han Solo that we see in the comic. In fact, it is canonically established, in Legends, that Han Solo had a couple of cousins. Therefore, it is reasonable to assume that the branch of the Solo family that generated Jacen and Jaina might not be the only branch of the Solo family in existence. Therefore, it’s possible that the Han Solo from the comic does not even come from the same branch of the family from which the Solo children come. And even assuming that the Han Solo we see in The Star Wars is a descendant of Han Solo from the movies, it’s not crazy to imagine that some of Han’s descendants might be aliens. This happened in the Legends universe already, and inter-species relationships are perfectly possible in the Star Wars universe.
As for the character called “Darth Vader”, it’s not difficult to explain it either. Given that this story is supposed to be set 500,000 years after Return of the Jedi, I think that you can easily assume that what happened in the original Star Wars saga became kind of a myth in the Galaxy over time, like we see the Bible, or the homeric poems today. So, to give someone a “mythological” name is not so absurd. A lot of people give their children mythological names in real life, too. Moreover, we don’t even know if Darth Vader is the actual name of the character, or if it’s just an alias that he uses. Maybe, it is possible that his name is not even Darth Vader, but he started to call himself that way after reading some old text about ancient, mysterious mythological figures and events. And after identifying himself with this mythological figure called Darth Vader, he basically said: “Well, I will start to use that as my alias.”
And finally, Princess Leia from the comic is not even an Organa, so she’s probably just a random princess who happened to be called Leia. It’s not impossible. After all, how many princesses happened to have the same names during European history?
As for the names of the planets, I don’t think it’s an impossible task to reconcile it with the original Star Wars saga. Planets and places just change their names over time. Therefore, it’s not so absurd to assume that certain planets changed their names. For example, Alderaan from the comic can actually be another planet, that people started to call Alderaan over time, even though the original planet was destroyed by the Death Star. I mean, things tend to change a lot during the course of 500,000 years, you know.
I’m sure that more than one person is probably thinking: “Okay, all of this makes sort of sense. But how can you explain the fact that the technology is pretty similar to what we can see in the movies? If the story is supposed to be set 500,000 years after Return of the Jedi, how is it possible that the technology is very similar to what we see in the Original Trilogy itself?”
Well, I don’t think the technology is a real problem. In the comic it is implied that the Empire controls the entire Galaxy, and in the background of some scenes, you can even see aliens that resemble the Chiss. So, you can assume that the Unknown Regions were completely conquered, discovered and peacified, which is a great advancement compared with the original Star Wars saga. Not to mention, astro-droids have the ability to speak like normal droids in the comic, which also is a great advancement compared with the original Star Wars saga. Furthermore, more than once the comic gives you the impression that hyperspace travel is much faster than in the original Star Wars saga, so you can reasonably assume that hyperspace technology and travel advanced a lot, and that hyperspace travel is even faster than before. Therefore, even though some of the technology remains the same, a lot of other stuff is more advanced. I don’t think it’s really a problem anyway, because the advancement of technology in the Star Wars Universe has always been irregular and incoherent.