The Egyptians have Ramses

Uh? Ramesses was human - all 11 of them were. Egypt has the likes of Ra, Osiris, Anubis and so on, who I don’t think are particularly tyranical in their stories.

For China, the actual mythology stuff is a lot of creation myth, but they do have a few stories about a divine emperor crushing an army of demons, and it turns out a lot of that is actually about conquering less developed, more nomadic cultures to unify China (Japan pretty much did the same, creation myth then crushing foreign demons that are actually literally foreigners not under their rule). And then there’s the whole mandate of Heaven that they used to justify dynasties rising and falling, mixing up history into myth, that began when a government that started well ended up being seen as tyranical after a few centuries (the Shang, ending with Zhou and Daji).

Older, more primordial mythologies just start at world creation myth, and then talk about humans figuring out how to settle the land, and how the universe works. Mesopotamian cultures mostly focus on defeating the forces of nature, which does involve standing up to violent gods or monsters, but that comes from trying to build up a civilization that can survive disasters, and is actually not tied to tyranical human rulers. Any civilization needs to start with things like water control, that’s why everyone from China to Greece also have that. Sumerians specifically have cities that go to war with each other because “the chief god of their city told them to”, which is obviously manipulation to secure resources, but isn’t particularly tyranical against their own people. And then the Bronze Age Collapse happens, after which the myth of Ishbi and Erra shows a war god who gets petty and kills everyone because people didn’t pay attention to him. So again, the stories of tyranical gods come from people trying to survive and explain destruction events, from nature or from outside forces. When the Assyrians go around killing everyone, Sennacherib destroys Babylon out of anger and frustration - he tries to write a story about the god of Babylon ordering him to do that, and another story of his own god putting the same god of Babylon on trial for some crime, but that doesn’t stick and Sennacherib gets murdered.

At some point it’s not easy to distinguish mythology and simply literature. For China specifically, Journey to the West and Investiture of the Gods talk a lot about the bureaucracy and hierarchy of the Heavens, the oppression of gods and demons - but they’re 16th century novels, are they really mythology? Those stories clearly became popular because people felt oppressed by tyrants, so the myths about tyranical gods can of course be a reaction to the people experiencing tyranical rule. Sun Wukong’s story famously starts because the various systems of the Heavens can’t contain him (and mankind), only Buddha can - but then that’s still a 16 c. novel that showed up long after the creation of Buddhist “mythology”, its spiritual structure and divine figures.

So there’s multiple reasons for stories to pop up about gods becoming tyrants, either because the people get upset at actual tyrant kings, or because one country tries to justify the destruction of another country. But there’s a distinction to be made about stories written as piece of literature and when they become actual civilization building myths that is a fundamental part of its culture. The older a civilization develops and gets centralized, the more opportunities you get for anyone to write more stories that become myth a few hundred years later. If that civilization has ups and downs, the stories about gods are more likely to reflect that. (I think Egypt got out of that because it actually collapsed 3 times, and kept starting over with new gods doing the same things, none of the unified kingdoms lasted more that 500 years)