A high-brow British quiz show asked, QI: Who created the theory of relativity? - BBC.
Einstein is the wrong answer. The host says that maybe he created the special and general theories, but Galileo created relativity.
The show is ridiculous. Galileo wrote a 1632 book advocating heliocentrism, and had an argument about a ship, saying that we might not feel the motion of the Earth. This is supposed to be the beginning of the Principle of relativity.
But the same heliocentric argument was made two millennia earlier by Pythagoras and Aristarchus of Samos. Einstein did not even really believe that the Earth's motion was undetectable, as he believed (incorrectly) that it caused the ocean tides.
The modern relativity principle comes from Maxwell, Lorentz, and Poincare. Einstein had nothing to do with it. The details are in my book.