It most likely was a speed run, yes.

You don't get AOE at first, but you will by about level 40 on all classes. It's good that you are thinking of using AOE, because a lot of people actually get to max level and still don't do AOE. Tanks have AOE from the first dungeon because they need it to hold all of the mobs properly and that's why they will speed run that early.

To help with keeping up with the tank, press Sprint. If you haven't attacked any enemies yet, it will last 20 seconds instead of 10 seconds.

I would recommend not trying so hard to attack until the tank actually stops because it's not likely to work. The game usually considers the enemies further ahead than you see them because of ping.

The dungeons are not hard in general but they do get more mechanical and beautiful as you get further on.