So "intent doesn't exist in any meaningful sense?"
You're requiring me to first solve the hard problem of consciousness before making an argument you consider credible but I have yet to see a counterargument on your part which meets the same criteria, and you would need to do so to prove my statement is a "house of cards" versus simply an opinion with which you disagree.
I think yours is the more difficult argument. I can't really grasp a definition of art that doesn't presuppose intent.
Imagine any Ansel Adams picture was taken by a monkey. Are they suddenly trash? Imagine your favorite haiku was instead created by a parrot mashing together overheard snippets from its owner. Again trash? The argument gets frighteningly literal when you consider people like Jackson Pollock.