Cipher or unknown language - historical perspective

[Koen G]

To me 

Ég hef ekki hugmynd um hvað þessi setning þýðir.

looks very foreign, even though most character shapes are familiar. I have no idea how to read any of it and I would struggle to guess the language.

I'm pretty sure they would recognize this as a Germanic language. Without speaking any Scandinavian or looking this up, I can guess from my knowledge of English, Dutch and German:

eg - I, ik, ich
hef - probably have, heb, habe
ekki - okay, this one is weird, I know "ikke" is a negation in one of them (Norwegian maybe) so I'll cheat here and guess "not"
hugmynd - no idea but one could guess the word "mind" is in there, it feels Germanic.
um - similar to Dutch and German, might mean something like "about"
hvad - there's a strange symbol here which might throw someone off, but this word should not be a problem for an English speaker at the time: what.
þessi - same, though again similar to West-Germanic.. German MSS often say something like "disse", Dutch "deze". 
setning - from context I guess this means "sentence". But again, crucial is that it looks Germanic, with the -ing suffix.
þýðir - okay, this word looks foreign, but again not to the extent that one would think it comes from Egypt. Links exist with Dutch "duiden", German "bedeutet etc, but that assumes one understands how to read the non-Latin characters.

So my guess is that you typed something like "I have no idea what this sentence means".

My point is that this script is still based on Latin writing, with one class of unusual characters thrown in. Add to that the fact that Scandinavia was connected to Europe, especially northern Germany, and I don't think this would have caused the same reaction.

It all depends on one's frame of reference. It seems clear to me that Baresch and his peers had no clear frame of reference for Voynichese. But I wonder if the same were true for someone working in a c. 1400 scriptorium.