Apparently you don't know the meaning of "myth." A myth is a story. Your example about New York and America is evidence of you not knowing what is a myth. You start out by saying someone writing a story about the year 2000. Then you talked about New York and America. The myth is about the year 2000 and not the city and country.
So the "Exodus myth" is the story about Moses and how he lead his people out of Egypt. The myth is not about Egypt. There can evidence of a place called Egypt as described in Exodus, but doesn't make that story historically true if there is no evidence of Moses and his people being slaves in Egypt and of their journey traveling out of Egypt. Information about the land is not evidence for the Exodus story. Evidence are information that support the event(s) that took place.
In the example of the Spiderman myth, it's about him being a hero in New York, and not New York itself. So if 2000 years from now, archeologists find the ruins of an ancient city fitting the city's description, that's not evidence for the myth of the hero named Spiderman. That's the difference between information being evidence supporting the myth(story) and information not does not support the myth(story).
Today we have evidence to support that was a ship that sunk into the bottom of the ocean. That doesn't mean that it's evidence for the event when Rose choosing not move over just a bit so that Jack could climb on the board, and didn't had to freeze to death. That's what is known today as being the genre called, "historical fiction."
Read this three times and not sure if we are on the same page.
Yesterday I read about Pliny's account of the eruption of Vesuvius.
Pliny wrote something that was not believed until recently - it's
called "pyroclastic flow"
This adds credibility to the Vesuvius account - not that it happened
but that Pliny, writing 20 years after, was more accurate than some
thought.
With excavations at Shiloh we have added credibility there was a
cultic center there, and that the priests were sacrificing in the way
they were instructed to in Leviticus - one of the Exodus books.
A bit like Pliny.
We are missing tons about the ancient world. Until recently the
story of Edom's population was not believed. And slowly, towns
and structures from Israel monarchical days are coming to light.
We have no evidence for Hebrew slavery - I accept that, but with
the caveat that any Egyptian archaeologist digging up Hebrew
relics might need a change in career. This happens even in our
Western culture.
Absence of evidence doesn't' render something a "myth" but
that it has "qualities of myth." Only the Hebrews admitted to
once being slaves.