That's a reasonably fair assessment. Creativity doesn't exist in a vacuum and I agree that some clear influences prevail through his sound. But then I can listen to Radiohead and hear clear influences coming through their music too. Admittedly more developed than Blake's, but they're there all the same.
After thinking about it further, 'unique' was probably the wrong word, what I meant was 'novel'. He presents and contextualises his influences in a somewhat novel way, which has been emulated by quite a few others. I guess that's not on the level of being 'unique,' but still an achievement.
Though I definitely agree that it feels like this iteration of his sound has run its course. I've never been that big of a James Blake fan and this album has done nothing to show me that he is, like you put it, maturing. He's perfected a certain aesthetic and at this point it feels like art is turning into craft.