Is there a concept which describes that the first discoverer or creator would not necessarily have been the only one?

Just because Steve Jobs lead the company that developed the iPhone, does that mean that nobody else would have ever created it? Or that they wouldn't have created something better?

Same for Dennis Ritchie, this says we would have no Unix, no Windows, no C, but wouldn't somebody else likely have come up with other similar methods for accomplishing the same tasks?

Not to take away from Mr Ritchie's accomplishments, clearly, that one individual had their hands in all 3 shows that he must have been a genius.

This is what is called a false dichotomy. I could for example point out that Dennis Richie gets more attention than say… Norman Borlaug.

Life and dying is not a competition.

Steve was an amazing business man. Dennis Ritchie was an computer scientist / innovator. A computer scientist will innovate things and build things. A business man will glorify things and sell them to the people and hence people are more in contact with the business man then the scientist which will lead people to praise business man more.

Neither one could have done what the other did, and trying to downplay what one did to pump up the other is really not fair to either of them.