A bag of hammers, Oreos and Paris Hilton are inanimate objects.
It would be inappropriate to cast a vote for myself; also - dumbassery - while a trait of MODMAN, does not fully encapsulate the scope of MODMAN, in my view.
Therefore, I cast my vote to Blackfoot. He / it is the epitome of dumbassery. Pure dumbassery. Completely lacking in self-awareness. There is little else to Blackfoot beyond dumbassery (save for a greasy, cum-stained chin).
Anyone who believes in "New Age" Spiritualism is a tight second.
Honorary mention: The Question - a keen, sharp mind - regrettably turned to seriously dumbass beliefs / points of view. They are wrong. But is being so wrong in your outlooks / perceptions make one an irredeemable dumbass? A Question for another time, perhaps. They weren't included in the poll, so we'll leave it there.