As others said, you can take your time. Unless it's a multiplayer server where others are beating the bosses while you do putz around, it won't ramp up on you. There are even ways to advance beyond your current game difficulty. Like normally you get the means to make the pick from the first boss so you can start mining, which would then let you make a better axe to get those trees that currently say "too hard", but as it turns out, trolls are able to break both those trees and the ore deposits, so you can actually reach the bronze age without ever facing the boss and increasing your overall event difficulty.