Charles Darwin was a scientist who had a theory and discovered natural selection and evolution. He traveled the whole world, and had a journal with him, taking notes about what are different or peculiar. However, this didn't mean that he did all this alone. He learned from other scientists, and mixed those with his theories and predictions. A scientist helped Charles Darwin understand that evolution went very slowly. He learned that over generations or decades, evolution has developed little by little. This could be affected by environment, or changes in the earth that the species lives in.
Charles Darwin didn't discover natural selection by himself. He had much to learn from when he first started this discovery. To me, it's mostly a shame of how most people don't note that other scientists helped Charles Darwin. They just thought that he did it by himself, even though it was completely different. Sure, he inspected and created his collection, but did he know what they were gonna be used for? Yes, he did. But did he know where to start? That leads to the extra help from the other scientists.