I've got an idea about the link word. Assuming it's an anagram of the last letter of each answer, and given the answers that we're reasonably sure of, it could be "norites". Norite is a type of rock, and norites squares with "humanist ideal".
Just looking in. When I first saw 5 I thought it might be a proper noun- Big Essex bird being big S with ex-bird (extinct?).
Also tried square (thinking quare might be obs. eccentic/bird), something a bishop must go over (on a chessboard).