Having grown up in a family with two newspaper photographers I have inherited thousands of negatives from as far back as the 1920's. Unfortunately, neither covered sports very often. I had a bunch of baseball, but I sold them in a Hunt auction. I have no clue what to do with the rest of them.
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I would add that it is possible to create a negative from a photo. There once was a thing called a "copy camera" that made 4 x 5 negatives from a photo, but as others have said, it's pretty easy to tell. The photo below is original, but the negative is not!
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Good old "Hooks Dauss" from the ones I sold.
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My dad also spent a day in 1976 with Mark Fidrych, covering him from morning 'til night. I have slides from that assignment.
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Last thing I'd add is that glass negatives can really degrade quickly - moisture is poisonous. I think this one is of a car crash - poor tree.
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