This is a very flat view - the Roman empire is born in a period of civil war, and after a relatively brief period of peace in the imperial core starts imploding and rebuilding itself in different configurations.

The art and culture was very often echoing an imagined past of yeoman landholders + citizens.(very similar to the invocation of 'Real America' today). And their foundation myth imagines that they are a continuation of the trojan civilization.

For everyone who was not at the top of the imperial hierarchy it's pretty easy to imagine that they thought civilization could be improved! Aristotle writes a defense of slavery - which implies that someone was attacking the institution. It's not a big leap to think that enslaved people could picture a world where they weren't enslaved, or that women could imagine having political/civil/property rights.

I think maybe something you are getting at is that those structures felt indestructible at the time, that in christianity associating the end of the roman empire with the apocalypse. Needless to say we aren't posting this in latin.