Seems to me that you’re saying that the expression is about one particular Friday and not all Fridays in general. As when a group of people are putting an event on their calendar and one gives his/her opinion: Mmm... “I like Friday.” Otherwise, “I like Fridays” is more natural to the American ear to show preference for a day of the week.
Incidentally, how do you say “I like Fridays“ in Greek?
For interest's sake: The Greeks borrowed 'gustare' from the Italians (from the Venetians, to be precise), and 'gusto' too. See here (especially the second definition after the ||) and here. Young people use 'γουστάρω' and 'μου γουστάρει' a lot, and I am not very familiar with its use. Maybe Troll or one of the other native Greeks can comment.
Γουστάρω is used colloquially only. It is somehow 'stronger' than like, also used as to fancy which also means to want, not just to like. In that respect, γουστάρω is often used to describe someone's actions in the phrase 'κάνει ό,τι (του) γουστάρει', meaning, 'does whatever he likes/wants', regardless of rules, other people's feelings etc.
In short, γουστάρω comes with swagger! :D
It's like that because for the Jews, it is the day of "production or preparation=παρασκευή" of everything they will need for their most holy day, the Saturday. However, christians eventually moved the Saturday's holiday to Sunday, but the name stayed still. The same way Σάββατο>Sabbath="He rested" stayed the same.
https://en.wikipedia.org/wiki/Attic_calendar and the more general https://en.wikipedia.org/wiki/Ancient_Greek_calendars make no mention of weeks at all; it seems to me that there were only months, in which the days were numbered (not named).
https://en.wikipedia.org/wiki/Week#Days_of_the_week gives Greek weekday names which are straight translations of the Roman ones (i.e. Moon's day, Mars's/Ares's day, Mercury's/Hermes's day, etc.). From the context, this seems to be a Roman Empire thing, though, rather than a Classical Greek thing.
I think not.
That's trying to translate word for word but (a) I don't think the result is particularly natural English and (b) I don't think it's even that close to the meaning.
"appeal to" is a bit better than "please", I think, but the most natural translation of sentences with αρέσει generally involve the verb "like", in my opinion.
Similarly, I would translate Μου λείπεις as "I miss you", and not as "you are missing to me" or anything contorted like that.
Such translations may or may not be useful to remember how the Greek phrase works, but they're not good, natural translations as in what Duolingo expects.
The Greek αρέσω does not mean "like" -- a more literal translation might be "appeal to".
The subject is the thing that is appealing, and the experiencer who finds that thing appealing is marked like an indirect object.
So a literal translation would be "Friday appeals to me" -- η Παρασκευή "Friday" is in the nominative case, and μου "to me" is in the form that would be used for an indirect object (here: genitive, because it's a pronoun; a noun would take σε + accusative).
It's similarly to French plaîre or Spanish gustar or German gefallen, where the appealing thing is the subject.
But in English, we usually say "I like Fridays" rather than "Fridays appeal to me" or "Fridays please me" or something like that.