No....Led Zeppelin did not copy all their material.....they expounded dramatically on a lot of fairly primitive blues numbers
As did most rock and roll and rock bands.....the Stones for example who also expanded country original riffs via Gram Parsons and Bobby Keyes.....Clapton too....both genres too btw
If you want the long explanation I can do that.
Very few popular music acts didn’t incorporate something prior
The early Miss Delta boys heard it first in some form from Patton or Broonzy or some old cowboy or minstrel who God forbid might have even been white and taught them real guitar.... perish the thought
That's true. Anyway, their high point was as the backing band to Donovan.