The Greek people seem to disagree with this history.
They believe it's been advanced by western, media culture who are trying to advance an agenda.
My sense is that there's more to the story.
As a student of the bible, I know that the bible has thousands of times more attestation than does any of these greek stories. However, it is put under serious scrutiny.
My point, these could be aesop's fables for all we known. They could be anything promulgated by any historic enemy. You simply don't know, nor do I.
But I do know this. One book doesn't tell the story of a culture any more than reading ONLY "It Takes a Village" 4000 years from now, will be the truth of our era.
And imagine if all that was preserved was something from Elton John????
Literacy was by no stretch universal in ancient Greece. You do not have much in the way of trivial, niche scrawlings that distort the record - and what you do have in that sense (e.g., graffiti on potsherds and rocks) was just as likely to be homoerotic as anything else.
The literature that we have falls into four main categories: philosophers, storytellers (inc. playwrights and poets), historians, and administrators. There was some overlap, particularly between the historical tracts and administrative items. The material that they left behind was clearly written for widespread dissemination in the very core of society. It was also clearly directed at the mainstream of their respective societies, even when expressing contrarian or adversarial viewpoints as was not rarely the case.
The literature that was preserved by the Romans was even more clearly the crown of Greek intellectual production ... usually transmitted precisely due to its estimable value in Roman view. Moreover, there is no ambiguity whatsoever about the veracity of Aesop's fables, by example; they are characterized precisely for what they are. It is a rather simple exercise in reason to figure out where a particular work fit into Greek society, and either the Greeks or Romans tended to make a point of referencing that themselves as the side-benefit for the obtuse.
Yes, I think the portrait of ancient Greek and Roman civilization is patently clear and if the equivalent of Elton John wrote something I think that would be rather clear as well. Of course, I can't really think of anything Elton John has written that would transmit a misleading perception of our culture to future generations, but perhaps you can..
Finally, we also have plenty of Christian commentaries that catalogue similar cultural phenomena beginning in the late 1st century AD. I assume you reject the veracity of those as well?