Level 16 PUG is apparently not high enough to create a thread of my own, so I'm forced to ask in a ninja based post, sorry!

I'm a new player trying to build a ninja, but I've just gone over the level 16 PUG cliff on my way to my airship pass. Can I still build up as a viable Ninja or should I just make this my Monk and level up a new Ninja? Not being able to get my Rogue job without the airship pass was a surprise -_-