Shang, and all of the post-dynasty collapse centuries like The Spring and Autumn Period, were not great times to live in. Dismal and evil vibes, for the most part, unless you happen to be a mighty hero or bandit-lord who believes that he can conquer the age. Even so, most of them ended up in soup pots.
Notably the Tang Dynasty in China was concurrent with the Taika Reforms, Nara period & beginning of the Heian period in Japan.
There's some truth to this. The Japanese preserved certain Tang Dynasty customs which were lost to China, and they have some of the best collections of Tang-era artifacts.
This line of thought was, however, used in very unfortunate WWII-era propaganda, like "we have to invade China to rescue its civilization, only we can do this!"
I'd argue its difficult to find major aspects of Japanese culture that don't trace back to ancient China (maybe the language, eating raw food and sumo)
[0]: https://en.wikipedia.org/wiki/Late_Shang#/media/File:Shang_d...
[1]: https://en.wikipedia.org/wiki/Rhinoceroses_in_ancient_China
Shang being an villain fits this narrative.
Including a rather unusual battle between the Tang Dynasty and the Abbasid Caliphate:
https://en.wikipedia.org/wiki/Battle_of_Talas
It's recorded that the Caliph, on hearing of the battle, said "What is this? A crossover episode?"
A timely reminder that, damn, China is olllldddd.
There are some nuances about this. We know that there are multiple developed cities (and likely monarchies, given there are palace-like ruins) around or before Xia era. It's just that we don't know which one is so-called Xia Dynasty. But it doesn't meant that there were only small tribes and suddenly Shang came out of nowhere.
Troy was indeed largely fabricated though! Really I think that's of a piece with stuff being, y'know, really old. There are big holes in Sumerian and Egyption history too (though the latter helped out a ton by digging secret tombs and hiding them really well). Post-classical Mayan history is pretty suspect in a lot of places, etc...
There are people who believe that Trump won in 2020, that vaccines cause autism, and that the Holocaust is a hoax. You cannot reason people out of an idea they didn't use reason to arrive at.
There's just a substantial bias where people assume all 'new knowledge' is wrong. Probably correct most the time, but still often wrong.