Before Copernicus and Galileo, most of European 'academia' was holding steadfast to the ideas proposed by Aristotle and his legacy. The heavens where unchanging and divine - as clockwork, engineered in such a way that the divine human capacity for logical thought could understand it and predict it. And Earthly life was chaotic, dirty, and transient, with all regularity and flux a side-effect of heavenly or humanly processes: the divine.

Galileo's telescope showed these people a supernova. Moons around jupiter. Sunspots. Galileo proved that the heavens were changing, which did a lot to upset this worldview, and paved the way for people like Newton to do work independent of the Aristotelian world-view, and assert that the same laws that govern us on Earth also govern the heavens. (Let's also not forget that he correctly disagreed with Aristotle on the behavior of objects under the influence of gravity.)

Kepler deserves equal recognition, and he probably gets it. But really, they're both dead, so the important thing is for us to recognize what works and what doesn't. Not who found out what works.