Usain Bolt isn't even the 'greatest athlete' in this year's Olympics. That would be Ashton Eaton of the United States of America. And not only that, every single cornerback and 99% of the safeties and running backs in the NFL are better athletes than Usain Bolt. Bolt wouldn't last a single practice in the NFL.
There's a lot more to being an athlete than running in a straight line.