Many of these things weren't really effected by the Fall of the Roman empirical structure per se. Most of the things you mention didn't actually happen for a lo

Many of these things weren't really effected by the Fall of the Roman empirical structure per se. Most of the things you mention didn't actually happen for a long while after the empire fell. The first big plague happened in 541–542 AD and it effected people in the Eastern Empire more then in the former Western empire. Italian urbanization was not actually significantly changed until the Justinian roman wars where Italy was invaded by different armies over and over again. But important to know is that Italy was already less urban by the time the empire fell, Rome had already far, far fewer people then at its peak and had gone down over the last 100 years before the actual Fall. The point here is that many of the variables you describe had lots of variation within the imperial period and often didn't significantly change when the empire fell per see. So we need to be really careful as these things are pretty complex and our data is incredibly bad. Often informed not by good data.