First could still work. Rereading your passage, there's definitely some wry humor which could benefit from first. The thing about worldbuilding I mentioned is a bit easier in third, as an omniscient narrator can establish settings on a larger scale than a first person pov. But, if you can frame things well enough that the reader can infer most of the worldbuilding from context--which I totally think you could--you can avoid infodumping (the curs-ed scourge of fantasy!).
But neither except has an omniscient narrator. That style isn't used so much these days outside of children's stories.
Weirdly, that's what I want to portray. She's had a tough life, so she's become very disconnected and uninterested in the world. But she's become that way out of self-preservation. If you're weak, you get taken advantage of. If you trust the wrong person, they could steal from you. A sickness is growing and killing people quickly, so she pushes them away before she can lose them. And she doesn't do anything to help others, because, in their rough world, she doesn't think her small contribution will make a difference. She essentially thinks everyone is doomed and nothing is going to change that. So she keeps to herself and focuses on simply staying alive and out of danger. But she's still secretly hopeful. She wants things to change, she just knows she can't do it alone. And since everyone in their world is so focused on themselves and not helping others, anything she does could be easily undone. Most people steal and cheat just to get ahead, so it's become nearly impossible for her to trust anyone. And those close to her always disappoint her somehow. That's what happened with Loren and Adina. The three of them got into a huge fight and neither side was going to apologize. So Loren reached out to have Seren work for him. He knew she didn't need the money, and Seren knew he didn't need the help. Farmhands are easier to come by than food. But she figured Loren wanted to see her and spend time with her, so she agreed. She does minor things like that to show she cares. The beginning few chapters of the book are going to be about breaking those barriers in her. She's going to be forced into a position where she must fight or die -- literally. At first, she's going to accept defeat. And while she's living among a new group of people, she's going to see a lot of things that haunt her. But she ignores them because she has the strong mindset of, "don't get involved. You see nothing, you say nothing, and you'll be safe." She finally accepts her role and tries to do what's right. But she still has that cold personality for a while. A man who doesn't know her tries to help her, and instead of immediately accepting his generosity, she assumes he has an angle and wants something from her. Any time people misjudge her as being weak, she flies off the handle. Anytime someone does her wrong, she throws a temper tantrum. And this really never goes away. She works on it, but she's still somewhat angry and closed off by the end of the book. So maybe first is the best way to go. I really want readers inside her head, to feel her pain, to understand her anger. I'll write it in a way that she's a sympathetic character, so that they understand she doesn't want to be this way. She had to be this way to survive. But if first made it more clear that she's callous, then that's probably the way I should go.
I would go with first in this case. To me, it reads more naturally. When reading it in third person, it is easier to mix up who is who; The pronouns are clearer in first person.
