The goblins of the Cairn Hills have been there longer than... well, just about anybody. This isn't to say they're an especially wise or informed people, or indeed, that they consider themselves native. Goblins are a bit too ugly-minded to care much for history. Goblin religion revolves around the Old Faith, particularly Obad-Hai, Beory and Nerull, and they view the world mainly through a concept of cycles. Goblins aren't innately evil, per se, but they do carry a close-to-innate disregard for living things. They are deeply imbued with the Winter King's message that death is a necessary part of life, but take this to mean that killing is a necessary part of staying alive yourself.
There are neutral goblins, and even good goblins, but very few escape some aspect of neutrality in their alignment. A Lawful Evil or Chaotic Evil goblin is about as rare as a Neutral Good goblin. Some form of apathy is baked into the cultural mindset of goblins even deeper than cruelty.
Are goblins as whacky as they are in traditional Pathfinder? Do they have funny big heads and huge mouths? Well, sure. Many goblins embrace this nihilism and just go to town with it. Lamashtu is arguably a positive influence on goblins in many ways, encouraging them to be less passive, take more joy in things. Unfortunately, goblins that follow Lamashtu are under the thumb of the Barghest Heroes as well, who lead the goblins by examples of brutality and carnage.
There are three goblin "towns" of note around Diamond Lake: The Murkhollow, the Cinderhill, and the Crown Cairn, each named for their base of choice. These towns have established agreements with the Bronzewood Lodge over the years, and so leave the town, the Garrison, and the Lodge alone. Some come into town for work, but mostly, goblins care little for the "cliff people", as they call humans, dwarves, and indeed, most non-goblins.
The Murkhollow are fairly friendly, and many Murkhollow goblins are members of the Lodge. This doesn't make them any more pleasant to be around. Friendly goblins are, in a way, almost worse than unfriendly goblins. Goblins tend to make incredibly toxic friends, and people with anxiety or depression are urged to steer clear of them.
Are goblins happy? What a question. Maybe. Sort of. Evil people generally aren't very meaningfully happy. Goblins who adjust to being decent people are... well, at least they realize they're unhappy. Does it help? Maybe. Sort of. It's complicated.