Bleh. Roman Sunday and Monday are backwards. Sunday was named for Sol and Monday was named for Luna (it's late and I'm tired).
"So anyway I'm not sure what point I'm trying to make (if any at all), but suffice to say that we have heavy Norse influences in our language and some customs, but at the same time some things are way older."
I will conjecture that this linguistic link may have come through the olde English, from the Angles, Saxons and Jutes.
In days of olde, perhaps their language was much like your claim of Scandinavian influences.
It has been shown that the closest link to English is to the Frisian language, on the north coast of Holland.
In any event, the continental German and Scandinavian are linked and similar. But different, to.
Modern English is a complex mix, but almost all of the most common 100 words derive from Germanic roots (Germanic meaning all types of German).
In ancient Greek Monday is the Day of Selene, not Artemis. These were the days:
Sunday ... Heliou
Monday ... Selenes
Tuesday ... Areos
Wednesday ... Hermou
Thursday ... Dios (Zeus)
Friday ... Aphrodites
Saturday ... Cronou
In modern Greek, these are the days:
Sunday ... Kiriaki ... Lord's Day (or Prime Day)
Monday ... Deutera ... Second Day
Tuesday ... Triti ... Third Day
Wednesday ... Tetarti ... Fourth Day
Thursday ... Pempti ... Fifth Day
Friday ... Paraskevi ... Preparation Day (for the Sabbath)
Saturday ... Savato ... Sabbath Day
Not exactly creative, and actually borrowed from the Jewish system except for the Lord's Day (Sunday).
PS. The irony is that we have indirectly retained the pagan Greek day names but they abandoned them due to the association with paganism. As an idle aside, not too long ago I read a rather interesting article about the nascent revival of classical Greek paganism in Greece, with at least 200,000 Greeks (perhaps as many as 500,000) worshipping the Olympian gods and restoring the pagan mysteries. They call the modern adaptation Hellenismos.