General relativity is also the essence of Einstein's creative thinking. The mathematical basis of general relativity is Riemann geometry. According to the general theory of relativity, the mass of matter will bend space-time. The popular understanding is that massive objects at the cosmic level will cause curvature changes in the surrounding space and slow down time. From this perspective, one of the essences of gravity is the performance of curvature of spacetime caused by the mass of an object. The pioneering work of matter, energy, time, space, special relativity and general relativity points out the purest elements in physics and their relationship on the meso-scale and cosmic scale, which is the embodiment of Einstein's powerful innovation ability. Of course, relativity is definitely not the end of physical theory, and there will be more pure and essential basic physical theories in the future. Perhaps, the next Einstein will be born in China.
Back to the beginning, I think even if Einstein didn't put forward the special theory of relativity, other physicists would certainly put forward it. General relativity is indeed a little ahead of that era. Most of Einstein's contemporary great gods of physics have made great achievements in quantum mechanics. It is impossible for them to put forward the idea of general relativity in a short time, but they can do it in 20 years.