Any general romancing of past times is not Christian specific.
It's likely that the author was writing though a period of intense instability. Something like a major world war or two. That would for sure be an influence.
The Christianity we know today was the state religion of the Roman Empire. It's core doctrines were agreed on in a council summoned by Constantine the Great. But then the great ancient empire fell. It was replaced by many lesser kingdoms, which tried to keep some old traditions alive, and the Church was the unifying force. But then the Church itself split apart, and the last remnants of the old empire fell to infidels coming from the east. And then the Church split again.
The idea that the world becomes lesser over time used to be a core part of Christian worldview. Industrialization changed that, but Tolkien considered the consequences of industry and technology a great evil.
Roman/Greek mythology:
> Both Hesiod and Ovid offered accounts of the successive ages of humanity, which tend to progress from an original, long-gone age in which humans enjoyed a nearly divine existence to the current age of the writer, in which humans are beset by innumerable pains and evils.
https://en.wikipedia.org/wiki/Ages_of_Man
Hindu Mythology:
> Men neither bought nor sold; there were no poor and no rich; there was no need to labour, because all that men required was obtained by the power of will; the chief virtue was the abandonment of all worldly desires. The Krita Yuga was without disease; there was no lessening with the years; there was no hatred, or vanity, or evil thought whatsoever; no sorrow, no fear. All mankind could attain to supreme blessedness.
Your Roman and Hindu examples are spot on.
Progressive thought really is the exception and not the norm when I look at recorded history. You really only see it develop thematically as part of the Western Enlightenment. I think that primarily impacts so-called Western cultures, and in a sometimes contradictory way between sociopolitical and religious beliefs.
Caveat: I am not an expert in any of these topics. Just a hobbyist history/religion guy. I may be way off more thorough academic thought.
The success of European colonial empires started challenging that worldview, but some of the ideas remain strong. Especially in the parts of the world where the dominant church still claims it's the one universal Christian church. Of course, if you are a descendant of Protestants who fled Europe, your ancestors deliberately left that world and that culture behind.
The world degrades from the garden of Eden towards more chaos and finally the reign of Antichrist.
Only after that Christ emerges again, completely transforms Earth for a short while, and abolishes it altogether; the world ends.
I think you are missing a key moment, Christ being born. Christ’s life is the greatest moment in creation.
But Christ is born because the world needs saving. and the world keeps degrading after Christ ascends (returns, in a sense) to heaven. Prophetic activity ceases, miracles become more and more rare, etc.
After Christ, the world still tumbles towards hell, but now it has a hope to not completely end up there.
I would have a very hard time reading Genesis and then claiming that.
Is your point that, taken as a whole, the overall trend isn't so negative?
Quite true. OTOH, the "popular version" of recent Christian theology and myth has the quite un-enviable task of reconciling an all-powerful, all-knowing, all-benevolent God, who loves the humans who He created...with the actual (often horrible) reality that humans are stuck living in. Trying to do that generally requires a lorry-load of depressing plot twists, lawyerly double-talk, etc.
The "accuser" (Satan) says people only worship God because they get good rewards. If God doesn't reward them, they'd stop worshipping. God disagrees, and allows Satan to test his theory by inflicting great suffering on a righteous, blameless person (Job). Job's friends say "obviously you've sinned, and this is punishment from God", which Job denies. Job eventually demands God justify his suffering, and God takes him on a walk through all creation, effectively saying "you'll never understand divine justice, because it's way too complicated".
So this is not just a recent Christian question, but one that dates back to early Judaism.