Not of humanity. God had to do the work to save us and cover our sin. Sent His Son to save the world. Blessed is the man to whom the Lord will not impute sin. A SEAT represents a finished work.
Work is done, so one is seated.
All you need accomplished in order to get to Heaven has already been done. For by one offering he hath perfected for ever them that are sanctified. The Cherubims were part of the mercy seat. One solid piece of gold made mercy seat and cherubims. For we are members of his body, of his flesh, and of his bones.