On the subject of the idea of going back to the past in order to topple the Roman empire (as featured in https://mastodon.social/@WritingPrompts/101202238494596111): Why would anyone want to do that? It's pretty well known that the result of its collapse in Western Europe was a century of utter chaos, followed by a decrease in the quality of life. Contrarily, the eastern part of the empire, which didn't collapse and became known as the "Byzantine" empire, was way better off.
@lmintmate Among other reasons, the economic base of the Roman empire was slavery and they were as inclined to large-scale massacres as most empires.
@lmintmate (The destruction of the Temple is another obvious thing a time traveller might want to prevent. Or you could argue that Roman imperialism was the foundation of the European colonial empires, I suppose.)
@ghost_bird About the Temple, well I guess it's kinda sad that such a monument was lost, but going back in time and trying to topple the empire as if that would save the Temple would be going overboard. Even if it wasn't destroyed then, it was probably going to be destroyed at some other point, by some other of those who invaded the area periodically. As for imperialism, again Romans weren't its inventors. Large empires with conquering desires existed way before them e.g. Persia. (cont.)
@ghost_bird Even if Rome was more hands-on than Persia in having conquered people adopt its cultural elements (especially those considered inferior, such as celtic peoples), as evidenced by the existence of the Gallo-Romans, it still couldn't force everyone to throw all their native culture, even if they wanted to do so, because it was simply impossible to do so for such a large territory with the means of the time. Instead a whole lot of syncretism took place. (cont.)
@ghost_bird The causes of European colonialism were entirely different. They weren't so much because the great powers of Europe wanted to conquer stuff. They did want the physical resources, but they also went into a sort of "collectathon" of territories in a bid to prove who was the strongest European power. And also the "civilizing" aspect was way stronger there, because they decided that, as the "advanced" people they were, they had to "educate" those they perceived as less advanced. (cont.)
@ghost_bird This was even the case with countries that had a fair amount of civilization by themselves e.g. India.
In short, it's not like toppling the Roman empire before it toppled by itself (with the help of a huge wave of migration from tribes from eastwards) would have changed anything for the better. If anything, especially if the east part was also toppled, the situation would be way worse.
Sorry for the big answer, guess I just wanted to expand on my viewpoint.
@ghost_bird e.g. Ancient Greece also had slavery, so if that would be a reason to topple such a state, one might as well try to topple e.g. at least ancient Athens and Sparta. Of course with Ancient Greece not being a unified state, one would have to topple every single city-state - way more effort than it'd be worth. Not to mention that both slavery and massacres started happening way before Rome did them e.g. Sumeria had slaves and wars also happened since then, if not earlier.