Sure, but the end of Roman slavery was just the collapse of the economy. No one bought slaves any more so slaves became serfs - no longer sellable people but people tied to the land and coerced to work. That's hardly a sign of marvelous progress.

While still being a horrible situation serfs had significantly more freedoms than Roman slaves. Serfs were able to hold possessions, work for themselves, and did not have an owner that had complete freedom over them including killing them.

I'm unfortunately ignorant on history of serfdom in Western Europe, but serfs in Russia were effectively owned by landowners. Killings, corporal punishment, family separation were routine practices.

Roman slaves could own property including other slaves. They could be doctors, architects, teachers & other occupations that would be considered middle class today.

I would be really interested to read about the transition of slaves to serfs after the fall of Rome. Is this your own hypothesis or something that has been written about?

I think it was meant very much in the figurative way. In continental Europe, Roman society never really stopped, it just changed a lot. Even Goths and Lombards would try to "become Romans" as much as replace them, happily adopting titles and structures (with varying levels of success).

A big hindrance to seeing continuity is that popular knowledge of "romanness" is so focused on the late republican/early imperial era and there is surely not much visibly continuity between early medieval and a snapshot of the Roman state outdated by several hundred years.

Serfdom is just a mortgage by anyther name. Unless you own your house you are a serf too.