A simple class is the Red Mage, I would advice you look the class up, just know that you need to own Stormblood and have a level 50 class unlocked. Red Mage is pretty simple, their unique trait is called Duelcast, which makes every other spell an instant cast. In short you have 2 bars that need to be filled up, one is for white mana (filled up by casting white magick) and the other is Black mana (which is filled up by casting black magick). You cast Jolt, then proceed to fill up both bars. The only hard part (not hard at all) is to keep both bars balanced, so when you cast a black magick spell, next time cast white and vice versa, when both bars are almost full, you cast the melee combo.

Its alot simpler then it looks. I would advice you keep playing your Thaumaturge (at level 30 you can unlock Black Mage) As an Black Mage untill level 50 you only need to cast the thunder skill, Fire spells and when you get low Mana, cast ice spells.

This site shows everything about all the classes, including the skills and their effects: http://eu.finalfantasyxiv.com/jobguide/battle/?utm_source=pr_popup&utm_medium=popupbtn&utm_campaign=eu_jobguide

My advice would be to either play as the Red Mage or Black Mage, both classes are simple, but from personal experience Red Mage is alot easier, from rotation to dealing damage.