His brother, and the alliance leader are fairly relevant, and the author likely has plans to at least develop said brother more. Which is likely why what's happening here is being shown, aside from that nothing is really going on with the MC at this moment.

So Solo Leveling then 🤣

"Properly told" is entirely subjective though. There's just different styles of telling a story, and some stories take a step back from just focusing on the current main character(s) of the story to introduce new characters that are relevant to events in the world that the MC(s) will eventually be involved in/related to. That's what's happening here, which is perfectly fine.
The MC isn't really doing anything relevant at the moment, so breaking away to show what's going on in the world makes sense. If this were a movie where the MC was constantly involved in things like the Star Wars example you gave, then sure.

All the examples you gave are movies, which always have to be adapted/written in a way that makes sense in movie format. So they often deviate from the source material if they have one. Manga (manhua, manhwa, and webtoons), the long series ones, are moreso written with the idea of being read in a completed state rather than on a chapter by chapter basis. Which is why you'll get multiple chapters in a row, sometimes months or years at a time, where the Main Character gets little to no page-time.

Solo Leveling is one that does the opposite, it was written in a way that perfectly suits being adapted to the big screen, as it focused solely on the main character. All other characters were completely irrelevant, and we're just tin foil meant to make the MC shine more. Overall, an exciting read, but a very hollow story. Even the author acknowledged that.

What I don't get is why readers try to treat every story as though it were Solo Leveling; a MC dick riding festival, when they clearly aren't the same type of story.