I've had no issues up until the first 3-2 dungeon but by this point it's clear the game was made to be played in a party.
The issue, though, is that (apparently) close to no one is playing the game. I can't seem to find anyone either hosting nor joining the missions I'm doing, no matter how much I reload the party finder nor iddle on an open party.
I'm not able to finish this mission by myself the way I'm playing so here I'm am requesting either tips on how to solo (besides the usual "git gud") or finding people to play with.
You're right that the game was designed for party play. And you're right that the party finder is pretty much useless (at this point) for a low-rank knight trying to work through missions. But here are three ideas:
A. Stand in Haven and ask for help. Be calm and dignified about it. No one must think that you're begging, because players don't like beggars. You might make some new friends.
B. Join a guild. Your guild mates should help you, even if they take turns.
C. We could talk about your equipment here. Perhaps you've chosen weapons that make the game hard, or perhaps you're using the wrong damage type on the wrong monsters.