Thanks for the comment from Jack about John Philoponus. Another important earlier thinker in mechanics was John Buridan who was a natural philosopher at the University of Paris in the fourteenth century. He developed impetus theory, considered the rotation of the earth and suggested inertial motion. His works continued to be printed and published through the 16th century and Galileo would certainly have come across them. Today he is forgotten, together with all the other important medieval students of nature.
When I was an investment banker, we used to have to set up special companies for our finance deals. It was always fun to invent good names for them and I called one Buridan Finance Limited in honour of the forgotten genius of Paris. We used to challenge other parties to the deal to figure out the relevance of the name but sadly Google has made that a bit too easy nowadays. Still, I feel it was the right thing to give John Buridan a bit more recognition.