I don’t think there was just one, because what anyone contributes is a combination of a few abilities and efforts. Steve Jobs has himself repeated several time

I don’t think there was just one, because what anyone contributes is a combination of a few abilities and efforts. Steve Jobs has himself repeated several times during his career that it’s the intersection (or marriage) of technology and liberal arts and humanities that makes Apple’s products great. The first core competency was this vision — combining liberal arts and humanities with technology — explains the what, why and how of Apple’s most liked products. The second core competency he had was a deep attention to detail, though it can be argued that there were several bad products/issues and releases despite that. The third core competency was communication and presentation. Here too, one can read about the effort and attention to detail that goes into preparing for keynotes and product announcement events. To sum it all up, these enabled him to make technology seem like magic but yet relatable and useful in enriching people’s lives — whoever they were and whatever their profession. One example of how broad this has been treated is the emphasis on accessibility in Apple’s devices and software (compared to competitors). It wasn’t about the size of the market or market share alone.