Lonnie Donegan was a banjo player in Chris Barner's Jazz Band, and more of a musician than a lot of people gave him credit for.
I can't really agree that the people you mention would have inspired as many people to take up guitar, as he did.
He made it look easier than it was, that's what made people think they could do it.
Yes he covered the hits of others, it was very common in those days, and many of the covers were a lot better than the originals anyway.
Who had the biggest hit with Mr Tambourine man? Not the guy who wrote it!