Lots of musicians “borrowed” bits from others dating at least back to Beethoven and Mozart. The only clear cut case of absolute theft that I agree Zeppelin stole was Dazed and Confused. There was simply no justification for that.
M.C. Hammer pretty much lifted a whole song from Rick James.
Dazed and Confused was the one from the video that really stood out but the others were also pretty much note for note copies. Every bit as bad as the My Sweet Lord/He’s so fine ripoff by George Harrison.