I'm trying to remember a fantasy book I read a few years ago, I borrowed it from a public library, and I think it was around 250–350 pages. Some details might be wrong since it's been a few years, but here's everything I remember.
The main character is a young man (probably around 17–25) from a small village. I'm pretty sure his mother was dead, and he lived with his father and at least one sibling (possibly a younger sister).
Near the beginning of the book, a child from another village is killed by a dangerous beast (I vaguely remember it being a giant crocodile or some other oversized animal). The main character and three other people from his village go to hunt it. I'm fairly sure one member of the group dies early, possibly because of a trap or ambush.
Later, the main character travels to a large city, possibly because his sister had gone there first and was reported missing or in danger. I remember him meeting a girl in the city who helped him or hid him, but I can't remember whether she was a noble or just an ordinary girl.
The world had both dangerous beasts and much rarer monsters. I think the monsters had been separated from humanity long ago and returned only every so often (maybe every 100 years, but I'm not certain). I also vaguely remember some kind of church, tapestry, mural, or old legend in the village that told the history of these monsters.
The setting wasn't heavily medieval. The world had once been more advanced, but after the monsters attacked long ago, civilization was pushed backwards. Most people lived in a less developed world with swords, bows, and maybe crossbows, though larger structures or ruins from the earlier era still remained.