I think it's just a question of how you word things - "The first person known to have swum the English Channel" or "The first person in modern times". When it comes to the discovery of the New World, "the first Europeans" for example, might work if you want the answer of "The Vikings". Poor old Chris wasn't really the first anything, though you could frame the qustion "Whose discoveries opened up the New World to exploration by Europeans?".
When it comes to quizzes, this just reinforces a point that the editors are making all the time - not all players will be working from the same frame of reference, and you must make sure that your question actaully asks what you think it is asking.