If Jesus rose on the first day, wasn’t that Monday when the calendar was made? “Mon” or “mono” means “one”?
While many English words derive from Latin, the days of the week are not among them. The Old English translation of “day of the moon” was Mōnandæg; later in Middle English it evolved to be Monenday.
As for why Monday is the “day of the moon,” that dates back to the ancient Greeks, who named the days of the week after objects in the sky (the sun, the moon, the planets). Later, during the rise of the Roman Empire, they were given Latin names, and those Latin names are what has been translated down to different languages.
So the first day of the week, the day on which Jesus rose from the dead, is Sunday, not Monday.