I agree with all those who big up his influence.
What made him different from almost all the other artists mentioned was his energy. He was more of a British Elvis than Cliff Richard ever was.
It was his rhythmic drive that made skiffle as a genre so exciting. Of course he was supported in the beginning by excellent musicians, but he led from in front. His energy still comes out of those early records while most of his contemporaries sound dated and safe. His skiffle had a genuine rockabilly drive. They made you want to get out of your seat (or even rip the seat up), while most of the competition sounded like an accompaniment to a nice cup of tea.
One of the first LPs I ever heard as a child was his "An Englishman Sings American Folk Songs" - designed for the US market at a time when the statement in the title was a true novelty. The sound of the arrangements and production stayed with me - the intensity, sensitive phrasing and space in Nobody's Child and Alabammy Bound. (I still regard his versions of both as definitive - Leadbelly's Alabama Bound is good, of course, but doesn't have the same restrained yet intense feel. Not too sure about the backing vocals on Lonnie's, that's the only thing.)
IOW, it wasn't just that he introduced US blues to UK audiences, but he did it with a healthy dose of intelligent creativity and charismatic performance. That was the difference between him and the likes of Korner, Barber and Colyer. Of course those three were great musicians, highly influential on other musicians, and one can argue that LD "sold out", over-commercialising the material. But I think in the beginning he struck just the right balance - showed how the blues could give a voice to ordinary young British teenagers, not just be the underground obsession of a clique.
(I shall draw a veil over Chewing Gum and Dustman...)
There's a similar comparison, IMO, with the Stones in the 60s. They also took blues and made it charismatic and relevant to white youth, practically instigating a whole new genre (and were accused of selling out in the process - and left poor Alexis in the slipstream for a second time...). Who else could have done that? John Mayall???