Success isn't binary, I'd argue many could have been more successful.
NASA was doing some good work for years before Katherine Johnson came along. Heck, I'm sure people at the time would say that NASA would accept anyone that was hardworking and intelligent. Would NASA have collapsed without her? Likely not, but it was made better because of her involvement. You don't know what you miss out on by not accepting people.
She was given the opportunity to show that she was good at the job. The reason she wasn't given this opportunity earlier was because of her skin color. Others that were not given this opportunity due to their skin color are lost to time.
NASA was doing some good work for years before Katherine Johnson came along. Heck, I'm sure people at the time would say that NASA would accept anyone that was hardworking and intelligent. Would NASA have collapsed without her? Likely not, but it was made better because of her involvement. You don't know what you miss out on by not accepting people.