You simply have your facts wrong. Darwin's theory was the theory of evolution by means of natural selection. The "evolution" part was well known pre-Darwin. It was the "natural selection" part was the new and important thing.
"Darwin's theory was the theory of evolution by means of natural selection. The "evolution" part was well known pre-Darwin."
Please name the scientific theory of evolution that predated Darwin, and the purported means to accomplish that evolution.