I Can't Decide My Own Class?!

My life has ended - bummer. But, in a strange stroke of luck, I've been reincarnated into a fantasy world! It's almost like a video game - I've even got a strange voice in my head telling me how to use my powers and level up! Wait, now there are two voices...and I'm a mage?! A third - and I'm a thief?! The first one's back - AND I'M A CHARISMA BUILD?!