Oh yeah. Al has a lot of original songs, but they're usually "in the style of" someone. One that stands out for me, is "dare to be stupid" in the style of Devo. Very clearly in that style. But it's not a parody.
In so many cases, I would say that Al is as talented, or more talented than the people he parodies. Taking someone else's song and inventing new lyrics to it that not only make sense, but they're interesting, catchy and fit the song perfectly, can be a real challenge. He reproduces all the music with his own band, and of course also has original content too.
Looking at all of that and thinking "he's unoriginal" is insanity. He's weird, sure, just as his name implies, and that's what's great about him.