[Snake]

I agree, sorry but humans are not special or supposed to be, until we think of a reason why they exist.

I once thought: "Oh, but they use 42 aptitude, they gain 1 stat point to put somewh--" Nope, Hyattrs and Mechanations also have that. Especially Hyattrs, who have racials and a looot of benefits, including the possibility to become immune to fire damage.

Whatever 'healthy' benefit I could think for humans using SAN is that every 20 SAN they get +1 points added to their diminishing returns, as:

Imperials get the +1 (per 25 SAN) bonus on all stats.
Tannites get a +2 (per 25 SAN) bonus on STR/SKI.
Onigans get a +2 (per 25 SAN) bonus on CEL/LUC.
Chatarans get a +2 (per 25 SAN) bonus on DEF/VIT.
Lispoolians get a +2 (per 25 SAN) bonus on FAI/RES.
Karatens get a +2 (per 25 SAN) bonus on WIL/SAN.

I mean, they do have to survive their everyday problems (such as facing the deserts, dealing with every sorts of situation or studying magic), that must leave some impact in their bodies. The way it is, you can barely difference a human from another.

[Chaos]

The only races that SAN is really 'useless' for are the Corrupted. Every other race can gleam something out of SAN, whether they have the racials for it or not.

I also have to question why APT isn't used in Quick to Master (i.e. +(Scaled APT/10) SP), but I digress.

The only thing I can think of that would give SAN use for Humans while keeping them within their lore would be an optional Trait:

Divine Boon
REQUIREMENTS: 100 God Loyalty, 20+ SAN

Humans, lacking a patron god of their own, are especially susceptible to divine gifts. As long as you retain 100 Loyalty to your god, you will gain a racial skill, based off your chosen god. (The skill's effects are based off your SAN. If God Loyalty falls below 100, the racial skill is removed.)

I do not have any concrete ideas on what each God would grant at this time.

[Shujin]

Useless was maybe a bit over the top, I meant that the points are simply spend more effectively somewhere else, and outside of corrupted it´s more worth for everyone else, how it´s suppsoed to be, really.

But I am not sure how to feel about giving them some god powers from Prayer alone(and 20 san)...I kinda think the prayer meta is already strong enough, and doesn´t really need a extra for humans. But I guess thats only my opinion.
I honestly think simply making them master their classes better is a fair trade off. and two is kinda to little.

[Snake]

--Damn, Chaos' ideas are always nice. I'd revoke mine for that, it sounds more thematic on his way.