"The best humanity has to offer" seems like a slippery concept. If something goes wrong in retrospect, you can always find a reason that it wasn't the "best". How would you determine if a thing X is the best? How do you know the best is a very different thing from a "high risk" scenario?
That phrasing wasn't meant to be taken literally. It's an American expression.
"The best humanity has to offer" just means that people put in a good faith effort to obtain the best that they were capable of obtaining given the resources they had. It's a fuzzy concept because there aren't necessarily objective measures of good, but I think we can agree that, for example, Boeing isn't creating the best products humanity has to offer at the moment, because they have a recent history of obvious problems being ignored.
> How do you know the best is a very different thing from a "high risk" scenario?
Going to space is inherently a high risk scenario.
As for whether what you have is the best you can have: you hire subject experts and listen to them. In the case of Challenger, the subject experts said that the launch should be delayed for warmer temperatures--the best humanity had to offer in that case was delaying the launch for warmer temperatures.
