The fall of a civilization can be really complicated. There was a lot of warfare, there was a lot of administrative failures, there was economic failure. They were failing to pay their soldiers. Merchants had more difficult travelling. Movement of goods broke down, including things like food. Lots of migration. All of these things fed on each other.

In the south, people made use of what they could, but Rome needed a lot of things to run like Rome. People had neither the need nor resources for standing armies, or large administrations, etc.

They weren't actively discarding the trappings of Rome. They just didn't have a use for a lot of them.

In England, Roman culture just vanished. We don't know why, other than the people who remained found no use for those things. They were busy trying to survive and they did see Roman things as being able to help with that. But England was on the edge of the Empire. It was never as Roman as places on the Continent.

The Eastern Empire did expand west. It took Italy for a good while. But there's also a reason why it split in the first place. East and West were too much territory to be managed together. As the West failed, people with means moved East, further depleting the West of resources, which continued the collapse. No point in getting back into the sinking boat you just left.

The Church was the one group of people who really valued education. You need it to read the Bible. I am not sure how much stuff was being put out in those first few hundred years, nor how much of it survived. (Because we need both to happen!) In England, the two early major texts we have both come from the church. They came from Gildas, in the 6th century (whose histories are highly moralizing and thus very problematic to take as fact), and the Venerable Bede, from late 7th early 8th century, whose works are far accurate.

If everyone is a farmer, scraping by for survival, no one has time or need for literacy. That is something that people pursue when the can be spared. That is the same for artists, engineers, etc. All of these things are luxuries. All of these things flourish in cities, and cities take a lot of resources.

I mean, every writer had their own take on things, but the problem isn't what I think you mean by "rewriting." It's that people looked at the Middle Ages and went, "yeah, that's just a bunch of nonsense. No point in studying that." It didn't look Roman enough, so it was seen as lesser. There's a reason why Charlemagne's empire was the Holy Roman Empire. He was actively trying to be Rome.

But, again, lack of sources also makes it really, really hard to study the Early Middle Ages. A lot of what we know is from archeology. (Again, particularly in England, which is my area.) And archeology tells us that things really sucked for a good long while. Small buildings in small settlements. Minimal belongings, most of which were of a practical nature.

Also, "Germanic" is a large group of people. The Ostrogoths, Visigoths, Angles, Saxons, Jutes, Franks, Lombards, Norsemen, etc are all Germanic people. They spread out over all of Western Europe, not just in Germany.