Grendel calls the people he sees “pattern makers.” He means this in contrast to the bull he encounters before the men. What does he mean by pattern makers?

Grendel means that unlike an animal, humans don't operate on instinct. They are able to make and change patterns of their own. They have the ability to think in patterns rather than follow one dimensional instincts. They are a mosaic of thought. Although their thoughts can be absurd, they can also make them dangerous.