Attribute points are separated by class, yes. However Arcanist shares points for both Summoner and Scholar. if you know you want to run a healer, build it mind. You can reset them via Grand Company item bought with 250 seals, you get access to GC around 20 and build seals through fates and doing the dungeon/duty roulette.

as a solo player, you'll very much want to run a tank or healer up first; as the Main Story Quests takes you through 80% of the dungeons til 50. Queue times for leveling dps is usually really long. That said, finding a good/helpful Free Company (guild structured group) can see you get through it pretty quick either way.