Arkveld is the new "flagship" monster? What does this mean?

So, from what I've seen I think it's pretty obvious that Arkveld is not the main boss of the game - or at least imo. I think they're showing it off far more than I'd ever expect for a final boss. For example, in Wilds they didn't showcase Xenojiiva a ton, or at all. They they called it the new "flagship" monster. I'm confused what this means?
Is it being to be the equivalent of the new Rathalos, where it's a common enemy, but you see them a lot and they're like *the* powerful monster that likes fucking everyones' day up?
Or more like a Nergigante, where there's only one/a few of them but they're super powerful and take on the apexes of each region, and have more story presence? Something else entirely?
Thank you!

EDIT: Thanks for the responses, that makes more sense haha