I finally got around to listening to Led Zepplin I the other day...a couple of times I thought to myself "man, this sounds like the blues."
They really did claim to have written "Killing Floor" with a stupid title of "The Lemon Song." Howlin' Wolf had been to london and recorded with Clapton. Hendrix had played a scorching version of it on BBC Radio One. No way they could have missed just that one. Then all the Willie Dixon. It's embarrassing how often Page/Plant claimed to have written classic blues and robbed working folk artists. Lowered my opinion of them significantly to see it so if you want to hero-worship them maybe skip compilations like this:
https://www.youtube.com/watch?v=tiiY4ciKFQA
And that's just some of it. When they stopped doing it the quality of their output fell off a cliff.