Well - the way you describe it is it's like Satoshi used a bread knife to cut something other than bread, but it's more like he used it as an antenna. He is exploiting a feature of HashCash that Adam Back (who invented it) didn't even know existed. It has to do with multiple participants solving the same timelock puzzle in parallel and some very interesting stuff happens then - you should read the link I posted (I take it you have not read it), I think it does a fair job of explaining how incredibly clever it is.

But we're in complete agreement and that's my point, he took something (HashCash) and found out that it could be used for something it wasn't meant to. That's what's so clever about it. It's not like inventing elliptic curve cryptography designing the first internal combustion engine, it's taking something and realizing that it could be a lot more. It's not using a bread knife to cut something else, it's using a bread knife to create a more efficient battery. Or like using sleep as a sorting algorithm or figuring out that you could abuse the floating point representation to compute an inverse square root without actually having to compute a square root.

I'm not trying to diminish the discovery, it's quite the contrary, I think its simplicity and elegance is what makes it so impressive. It's a very elegant solution to a very complex problem and you could explain it in a few minute to somebody with the right technical background.