Yes, Jackson Pollock's paintings are art.
What a silly question.
I don't see that it's silly.
The definition of art is "the expression or application of human creative skill and imagination, typically in a visual form such as painting or sculpture, producing works to be appreciated primarily for their beauty or emotional power."
Where is the creative skill and imagination in Pollock's work? How is it any different than what a chimp might produce, if you gave it a bunch of paint and brushes? If I did train a chimp to imitate Pollock's style are you sure you could tell the difference? What if I programmed a computer to use an RNG to drip and drizzle a bunch of paint around in the manner Pollack did? Would that be art? Again, do you think you could tell the difference?