The "had" there was meant to imply it was true up until that point in history. Other people have either nearly matched or slightly exceeded him depending on the specific details of the later Apollo mission lunar orbits. However it is mentally easier to be the second person to do something dangerous once you see the first person succeed safely. There is a reason everyone knows Armstrong and Aldrin, but Conrad and Bean don't have much notoriety today in the general population.

At least according to usage that I'm familiar with, if the phrase were, "no other person has ever been", that would be talking about before or since. But "no other person had ever been" is only talking about history up until that point. "Has been" is the present perfect tense, and "had been" is the past perfect tense.