Oscar Pine my fucking beloved

Despite being this type of character that you think others would want no part of, Stan truly is an irreplaceable member of the community because there is no Gravity Falls without Mr. Mystery. Unlike Ford who spent his time in Gravity Falls in seclusion, to the point where no one in town knew him enough to call out Stan replacing him, twin or not, Stan is an active part of the community.

Everyone knows Stan. The grocery store employees, the Corduroys, the Northwests, the Gleefuls, the Ramirez's, Greasy Diner consumers, the press, the police, the town crazy (Fiddleford), children, older people, the mechanics, the tourists. Everyone knows Stan in some shape or form. He actively participates in their community by performing certain roles for people.

He's the convict, he's the joyful old customer, he's the boat renter, he's the diner customer, he's the business man, he's a man who needs a repair, he's a man with a story to tell, he's a man who has jobs for the younger people, he's the "third space" for younger people. Just like how he's had multiple identities, he also has multiple roles he plays to keep up with his appearance as this eccentric old man that lives in the woods.

Sometimes those identities give him a negative connotation, but he's been that way for so long now that most people see him as a relatively harmless (though not completely trustworthy) entity. Why else would parents of young children be so ok letting their kids spend time around him like in "Double Dipper" or "Summerween". Why else would Manly Dan allow his teenage daughter to work for him? The community knows Stan enough to see through the layers of him and recognize him as one of their own, despite being a transplant.

And the sad part is that Stan doesn't realize that he has become Home.

He is so dedicated to trying to bring his family back that he can't see that he has essentially built a family, a community, around him. I think we see that kinda come to together during the season finale when Stan explains that Fiddleford, who at this point has had very very very limited canon interactions with Stan, comes to the Mystery Shack with refugees for shelter. (Yes, this is peak jackass Stanley but honestly, at that point, he must have figured his whole family was dead and accepted it as is because the entire world outside was going to shit super fast.) But back to the point, Fiddleford and his group went to the shack. they could have gone anywhere else but they went to the shack for safety. Even the supernatural creatures went to the shack for safety. I wouldn't doubt that Stan, during his 30 years of living there, had some pretty significant interactions with the weirdness of Gravity Falls that wasn't just a passive bystander or a victim.

We of course have Soos assigning Stan as his father figure the moment he got hired

But Stan holds that moment dear too, with Soos becoming his main source of company after the Mystery Shack, his first big success, was starting to hit rock bottom. And he made sure to keep the screwdriver that led Soos to him for a decade which unfortunately gets stolen by a certain time traveler...

(Their meeting being a paradox of Soos' family leading him to them is super sweet too!)

Playing one game of catch with their dads still was a dream for both of them, even when it was clear that it'll never happen, even when Soos knows that the Pines are his family and he shouldn't care about that biological deadbeat, even when Filbrick threw Stan away like trash.

But both of them end up finding closure with each other anyway.