I would suggest upping the difficulty. There seems to be no challenge whatsoever with difficulty running at 1.06. I've never seen a hostile mob spawn, even in completely darkened areas. I'm not saying put it on hard or anything, but maybe change the default settings to Normal so hostile mobs will spawn.
The thing is this is Peaceful Farms, mobs don't spawn on the overworld. If you want mobs, go to /warp grinder, /warp nether, or /warp end to find some mobs. However, non-hostile mobs do spawn, like cows, pigs, bunny, etc. Also, I don't think mobs spawn around where there are places protected by Towny. Seeing that you've applied for staff and joined the forums and joined the server a few minutes ago, I don't know how this will affect your chances of being staff.
