While Aid, not only do I consider it not important, I feel it's actively bad to recommend to a new player because of the trap surrounding recovery vs prevention that often plagues new players in regards to Clerics (Which often takes them to the underwhelming Life Domain instead of the far superior Light Domain).
As far as I know, Aid is a universal spell which is available to all cleric subclasses, it is not exclusive to life domain. It also is not reactive in any way, because it is an in-advance buff that does not require any active resource spending. In order to take action you need to be alive, having some extra meat on those bones makes a difference between lying on the ground licking your own blood OR turning the tables in one fell swoop. I mean, calling extra health not important is kinda anti-newcomer friendly, at least in my book. There is a reason why the easiest difficulty mode essentially doubles HP of the party...
