Most of Hoenn's people trace their ancestry from four different lineages:
1. The people of the land:
The original inhabitants of Hoenn who chose to settle by Mount Chimey and live off of its lush soil. Created the Regis and the Claydol line to acts as protectors / workers using techniques now lost. Also created a braille based alphabet system that still persists to this day. May and the Stones are the descendants of them, although May finds the very idea of identifying with them revolting.
This once included a nomadic group of desert dwellers who created the Mirage Tower around their primary water supply. They've all either died out or been folded into the other tribes living in the region.
2. The people of the sea: The second group to arrive in Hoenn after being led there by Kyogre. ( The price was, of course, paid in blood, for the leviathan is not a kind being. ) Split into two main lineages, one of which settled in Sootopolis and another who kept up their nomadic lifestyle.
Archie's descended from the latter and his people remember their oppression under first, the Draconids ( nobody likes pirates, especially not the people trying to bring some sense of order to the region ), then the Japanese government and now simply under the realities of global capitalism forcing many of them them to choose between working for corporations polluting their home and starvation. Their communities tend to be more insular than the rest of the region, with Dewford in particular being known as a place that adopts strange trends.
The Sootopolians have been much more successful at maintaining their presence in the region's politics, managing to keep the spiritual center of their people mostly independent from the League. They settled on top of the Cave of Origin and therefore control the region itself and no, I don't mean just on a religious and political level ( because both are 100% true ). Used to act as the region's kingmakers back when the Draconids were the ascendent power.
Note on the Cave of Origin: There's some weird shit down there that Wallace doesn't know about and May barely understands. If she were to go deep enough into the cave, eventually they'll reach a point where they should have breached the mantle but it just keeps going. The very walls are lined with raw mega stones, the only major source of them outside of Kalos. The Draconids had very good reasons for maintaining good relations with Wallace's ancestors.
The Alolans are a minority that consider themselves related to the other two. And they are right, given that they've historically intermarried with the others.
3. The people of the sky: Pretty much only the Draconids remain, and even then they're very different from their ancestors.
Arrived in the region 3,000 years ago. Found Rayqauza on death's door and nursed it back to health. Their relationship with Rayquaza itself is a much more complicated matter than even most Draconids realize with their pact having been broken ( often due to their hubris ) and remade numerous times over the eons. The current incarnation is bound to May alone and no, she isn't happy about it.
The modern Draconids are the descendants of their people's royalty who fled when their kingdom was torn down by hungry peasants. Their bloodline has preserved their ability to control dragon types with anything from their words to a simple thought depending on the skill of the individual. A few have been born with the ability to use Dragon type moves; these individuals are seen as having the blessing of Rayquaza and as such, are often chosen as candidates for the position of Lorekeeper. Have actual, bona fide, dragon blood but unlike what their legends claim, aren't descendants of Rayquaza itself as that's physically impossible. ( Let's just say that the pool noodle has neither the equipment, nor the urge to procreate and leave it at that )
Note: Keep in mind however, that the Lorekeeper was always female before the modern understanding of gender rendered such things outdated. Not necessarily biologically female but their views on gender wasn't the same as our own.
Zinnia wasn't born with powers. Her grandmother had them but the recessive genes skipped a generation. She was never their first choice before Aster died in a horrific accident, leaving her protégé behind. Poor Zin was never anyone's first choice :')
The people of the sky have descendants all across Sinnoh, Johto and the eastern coast of Asia but they don't usually consider themselves as such the same way the Draconids do.
4. The people of the sun: Those from Kanto and Johto. No, they don't have any connection with Solgaleo or Lunala, the term is a reference to Ho-Oh. They used to be referred to as the children of the sun and moon before Lugia fucked off into part unknown.
They've had contact with the region since it was first settled. The Draconid writing system had major Kantoan influences during its evolution. The Japanese Empire annexed Hoenn under the threat of military invasion, using it as a source of natural resources for decades before the Great War blew them apart. The idea of a united Hoenn take shape under their occupation when groups who used to despise each other found a common enemy in those forcefully conscripting their children into a war nobody wanted any part of. Modern relations with Kanto and Johto are more relaxed although there's still some older folks who will break your ribs with the blunt end of a harpoon if you call them Japanese.
Everyone thinks wine from Johto tastes off and they're right.
The idea of Hoenn as a single political entity is an idea less than a century and a half old. The current incarnation of the Evergrande League is what happens when everyone decides that unity in the face of modern problems is more important than their divisions. ( It's also the product of generations of reform. The original version run by Devon Corp was downright oppressive to towards the working class. )