No, not really. Not unless unless it conferred a reproductive dvantage that made it more likely to pass my genes to another generation than someone without that adaptation. In the case of a person growing legs from their ears (which would never happen anyway for genetic reasons) it clearly wouldn't give a reproductive advantage. Extra appendages in an insect clearly could give an advantage, though. What is "beneficial" is what confers an advantage to survival.
Many examples of beneficial mutations have been directly observed. So we see that mutations can produce both new features and beneficial mutations. Tell me, what is to prevent several thousand such mutations over an extended time from producing a form of an organism that has little resemblance to the original (i.e. a new "kind" of animal)?