I mean no disrespect but your post reads like a Marxist version of Art History 101. Feudalism was not "destroyed" by the Black Death alone, nor was the creative impulse controlled by the imperatives of hierarchy, big guys- little guys or of politics. Totalitarianism, the state ownership of even a man's most fleeting thoughts, is a twentieth century historical reality.
Workmen became hard to get for example.
This happened. Now if Marx and Engels used this event as a justification for their theory, that's just tough bananas. There were, during the same period, plenty of other events to disprove their theory.