I'd speculated that the Husks are like us, but so thoroughly transformed that their minds are no longer intact. However, Jayce-san's findings on stasis present another possibility, given that the Husks originate as motionless shells...

[It's... incomplete, clearly. Akechi folds his arms, trying to connect the dots in his head.]

I do believe the state of the moon is at least partially at fault. The tenants within this world's religion consider stasis a great form of punishment. If the ritual failed, and that failure transformed the land, then they could be the remains of those who either failed the ritual or defied the moon in some fashion.