It depends on the person for example; Superman, if he looses his powers then he is worthless because he never train his body, doesn't know much about martial arts or gadgets and he is too used to take the blows because of his powers he can take, so If he were human he would be dead since the first issue. But there are others like Hal Jordan that without there powers they still can do or be heroes because they were train as soldiers. Finally the best example for this question is the Batman family that doesn't have powers but they are consider heroes because they are train for any kind of heroism.
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