Yep. If you listen to "hillbilly music" and "blues" from the 20s and 30s, or "rock" and "r&b" from the 50s or 60s, they are musically indistinguishable. The difference almost always solely lies in the race of the musicians or the target audience
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.