Diverse myths seem though to have the same source. Gilgamesh and the flood.
So one person made it up and subsequent people copied/borrowed/stole/repurposed it - I'm not sure that makes it any more likely that it's true. We have Christmas when we do because early Christians tried to overwrite the pre-existing mid-winter festivals; it doesn't make it true that Jesus was suddenly born in December, though.
A certain type of person dismisses myths per se.
I'm sure they do. Another certain type of person thinks their preferred myth is somehow qualitatively different to all the other myths.
Tribalism might stop some arbitrarily from enjoying other myths.
It might, yes. Stepping outside of that and seeing them all as cultural tropes helps with that, I find.
Being an expert in myths was instrumental in Lewis path to theism. There is no evidence he burned his books after conversion.
I don't know his history well enough to know, but I suspect he thought The Epic of Gilgamesh and The Book of Acts belonged in different sections of the library, though.
Lewis’s autobiography shows they helped him to categorise various religious narratives and identify what he called reportage. His academic studies prevented him from writing them off as one kind of load of old cobblers.
And yet innumerable other scholars categorise them similarly as archetypal stories, as cultural tropes and tribal markers. They've traced the development of the Christian god from an early tribal war-god amongst a pantheon through the Jewish development of Yahweh as a monotheistic deity, and onto the Christian mixed message of a monotheism with multiple other divine entities and a whole host of special pleading.
Your approach smacks of philistinism.
Oh, no, I've been called a name by Vlad. Well I've definitely lost that argument then... Your ad hominem smacks of someone without an argument to make, who just realised he'd resorted to an attempted argument from authority that rested on C S Lewis, but keep slinging those out, they're some of your best work.
O.