The three class archetypes Warrior, Mage and Thief are purely a lore feature that has no in-game relevance, it's for RP at best. It simply tells us of which general archetype those given skills fall under. In other words, it makes sense to call yourself a Warrior if you got a lot of those skills, but you can call yourself whatever the heck you want hehe.
If you wanna be the Ship's cook, then go ahead. Just don't expect to get a oily, black hairdue with a ponytail and crappy acting abilities.
