there are a lot of ranks in army.
Most people are privates however.
this is normal. Most of my characters are volunteers
Praetorian cannot be counted to the officer ranks. They were the guards of the roman emperor and his palace. A praetorian's rank was equal to the one of a common legionary but they had some additional benefits such as a higher salary, as well as a certain degree of prestige (not like the usual uneducated peasant/ citizen who decided to join the legions). The officers of the praetorians were also known as centurions and tribunes.