Before Galileo "invented" the telescope 3 dutch people tried to patent it simultaniously. One also described (like tesla) that hé reverse engineered it from writings by the ancients.
Many inventions simply happen when the environment is ready for them, e.g. manufacturing techniques have advanced to the point where something is possible.
Not terribly surprising, since using focused light to start fires was known to the ancients. From there, it’s not a huge leap to optics (however crude).
As I understand it, the Vatican astronomers called Galileo out on his claim to have invented the telescope. It didn't stop them from buying a couple of his scopes.
