Pieter Breugel the Elder was really funny.
Some of his paintings were clearly intended to be humorous, like this big famous one, Netherlandish Proverbs:
It’s a very large (4×6 foot!) rebus-like picture puzzle of various colloquial expressions, many of which we still have in English (the Wikipedia article has a listing of many of them). This painting is readymade for a funny execution, but nobody else could have packed it so densely with hilarious idiots: