In fantasy fiction Bards are often a "disguise" for assassins and spies. In a lot of those examples their real profession was archery(cause it's how they killed people anonymously). So going with "fantasy", there sure is a reason why ARC could become a Bard with the job system.

This is not real life, so taking ideas from fantasy fiction makes sense. Why would a ARC change into a RNG, cause both are pretty much the exact same thing...