Dude, if you genuinely want to know what happened, you should read some proper history of science. Here take this: https://arxiv.org/pdf/physics/0405066
It shows both how Einstein very much didn't make the theory alone, was inspired to take impotat technical steps by work of other thats that created a theory based on his principles before him, and that actually he first created (in intense collaboration) a failed theory that got Mercury's anomaly all sorts of wrong.
It shows both how Einstein very much didn't make the theory alone, was inspired to take impotat technical steps by work of other thats that created a theory based on his principles before him, and that actually he first created (in intense collaboration) a failed theory that got Mercury's anomaly all sorts of wrong.