Yeah, it's easy to blame the Germanic barbarians, but mostly it was the Romans' endless internal intrigues, corruption & civil wars that destroyed them. Some of the most famous and capable heroes of that last age of the Western Roman Empire who could've saved it were Romano-Germanic military figures, and the people who tore them down were Senators from ancient and distinguished noble families. The Senate and 'traditional' Roman nobility didn't make a single correct choice for pretty much the WRE's entire final century, from oppressing their proto-serfs so hard that the latter weren't motivated to fight for Rome or even thought barbarian rule would be preferable, to assassinating everybody who could've patched up the sinking ship of state.
For example,
Stilicho was a Romanized half-Vandal (father was a Vandal mercenary, mother was a Pannonian-Roman provincial lady) who beat the shit out of various barb invaders and was ultimately only undone by his own people leading a giant migratory wave over the frozen Rhine after defeating his Frankish allies who were supposed to stop them on the other side (they put up a good fight though, killed the Vandal king Godegisel). That was only possible because the
Eastern Romans were fucking with him so hard that he was preparing to go to war with them, at one point even derailing a successful Greek campaign of Stilicho's where he had trapped the infamous Gothic warlord Alaric and was about to kill him. Now after the crossing of the Rhine and the British revolt of Constantine III, Stilicho's enemies among the Italian Senatorial aristocracy (led by a certain supreme niggerfaggot named
Olympius) successfully conspired to push the Emperor
Honorius (one of the most useless emperors in late Roman history) to kill him, his entire family and then the families of the Gothic auxiliaries in the Roman army, which directly led to Alaric thrashing their soft untested Italian generals and sacking Rome soon after.
Also
Aetius, the guy who beat Attila on the Catalaunian Plains, was almost certainly of mixed barbarian descent. His mother was Italian and of higher birth than Stilicho's, but his father was from what's now
eastern Bulgaria and SE Romania. That province of Scythia was, by the 4th-5th centuries, more of a militarized march and populated by
foederati auxiliaries, mostly Goths (with some Alans and other peoples, even Huns, mixed in). Unfortunately he was murdered by the
other most worthless Roman emperor of the 5th century,
Valentinian III, who had been manipulated into doing the deed by the niggerfaggot Senator
Petronius Maximus (who promptly killed him now that his greatest champion was dead, usurped the throne and got Rome sacked by the Vandals).
Actually, the only major figure of the WRE from its final century of existence I can think of that wasn't some sort of Roman-German hybrid, be he hero or villain, was the
Emperor Majorian. Who did great things in the short time that he ruled but was tortured to death by the general Ricimer (basically a Suebic anti-Stilicho) with the connivance of, as you might guess, the niggers of the Roman Senate.