First of all, Adam, your essay was fantastic! You made a very credible argument for the identification of the Midgard Serpent with a mythologized version of a GS (either Architeuthis or Mesonychoteuthis). The Norse were indeed a seagoing people, and even for those who lived in villages, given the geographical location of what is now Scandinavia, the sea was never far away, and there may have been beachings of dead or dying GS's (just as there are in many coastal nations today).
Let us also remember that it was one of the Scandinavian languages that gave us the term "Kraken" -- which if my memory serves me, means "uprooted tree" (descriptive of the way a teuthid's arms look when emerging from the sea).
Secondly, a large percentage of myths do have their origin in ancient peoples' interpretation of natural phenomena, or attempts to explain these phenomena. Recently there was an article on a science website about the origin of the Cyclops myth. Archaeological researchers theorize that the ancient Greeks found Mammoth skulls projecting from the earth, and the large single nasal cavity in these skulls was interpreted to be an eye socket. That plus the enormous size of the skulls gave rise to the myth of menacing one-eyed giants known as Cyclopes, or "wheel-eyes". In the same manner, contact (even occasional) with GS's could have given rise to myths of an even greater monster of the same kind which circled the earth with its body.
Thirdly -- to Kiboko: I do not know the exact dates involved here, but I know that the Norse had a written language in the form of Runes for many centuries. (Many years ago I took an introductory course in Runelore, and it was quite fascinating.) Runes were used not only for conveying ideas but also for magic and divination. As in many pictographic languages (e.g., Chinese), each Rune symbolized an object, animal, or abstract concept as well as a sound or "letter".
As a were-ceph with a great interest in folklore and ancient cultures, I would be delighted to read more articles by Adam of this nature, and hope he contributes such articles to TONMO again in the future.
International Squid of Mystery