Only the pig dungeon is designed to be completed solo. The other dungeons are intended to be played with people. Either bring your friends or make new ones in game. That's the whole point of the MMO-ish style we're going for.
The leveling up is meant to be quick, because the slow grind of getting to end game content has always been an annoyance to us. Let's just hurry up and get to the end stuff. PVP or PVE.
That being said, we have left you a little in the dark as to what you should do after the tutorial quests are done. That was meant to get players to go out and actually explore. We want people to play the game and figure out their own ways of doing things, keeping the "light touch" approach. This might not be working as intended and further guidance may be added to help bridge the gap. IE quests to get you out into the overworld.