Natural selection has nothing to do with "survival of the fittest individual" or race, or species. It is all about traits within a species (species show variation due to sexual reproduction) that confer some advantage making it more likely that the traits are passed on. Hence the references to differential reproduction. Darwin did not disapprove of the term "survival of the fittest", even though it wasn't coined by him, but he was acutely aware of the potential for its misinterpretation and was at pains to point out that the concept referred to differential survival within a species and not between species (or races).