Hey, long time lurker, first time poster.

So I've recently gotten Scholar/Summoner to level 50 and I was wondering what exactly the connection is between Scholar, Summoner and Arcanist. Although they have their obvious differences, their similarities are striking. Is this just a case of three different civilisations creating similar techniques by chance (much like pyramids appearing in Egypt and South America) or is it that the job techniques (Adlo, Fester etc.) are the only "ancient" ones and are simply added to the Arcanist skill set?

I haven't seen any posts about this and it's been kinda bugging me. Any thoughts, lore mavens?