Overpowered

In this world nearly all of the population have some kind of superpower, everyone has their own special Quirk. No one knows who or where quirks first started showing up but it was soon reported all over the globe of kids developing quirks.
Zack has lived an average life with his mom and dad. He never excelled in anything really. All through elementary and middle school he got B's and C's never really feeling much drive to to try harder than that and he never really impressed anyone with his quirk which was that he had faster reaction times than a normal human, about 2.5x (if this gets more popular I'll give actual numbers and maybe revise chapters for a more realistic story) faster than the average human, he also can run at about 50 mph for large distances, he thinks that's his limit but who knows? He was generally awkward around kids and did not make any last long friends more just close acquaintances that they only talked in school and never outside of school with the occasional invite to a birthday party or two.
After middle school his family moved to a bigger city and the closest school was a private specialty school that had specific requirements about grades for an academic career but they ignored that requirement if the kid in question decided to join the hero course of the school so Zack knowing that he could not go for academics decided to try for the hero course instead which involves a different test that does not require grades. The story will start with him walking up the steps of the school getting ready to take the test.