The only thing I use Humanity for is Kindling bonfires, I never summon anyone and I am doing fine for the most part. Really feels like Insight is the better version of the mechanic.
No Mutants Allowed
Walpknut
TheGM
Having Humanity is how you get some turbo nerd neckbeard to invade your game so he can overwhelm you with the stench of 12 years without a shower.
Atomic Postman
It made more sense in Demon Souls where it stopped your health from being halved
Walpknut
For real, the only thing I have gotten out of staying human for any length of time are some people with weapons from farther into the game invading me, but I just chuck fireballs at them and killed them. Then they dropped a weapon I couldn't use because I am a Dex build and they just used ST weapons. I mostly just kindle the bonfires with humanity. Haven't summoned anyone even once.