No. You did not. By definition, and by what you said, you created a variation.
Just substituting a different material type doesn't create a new fly.
An example of a "new" or unique fly would be the rojo midge. Although it is a simple tie like any other midge pattern, the gill tufts and red bead are completely different than any other commercial midge pattern out there.
But then again, technically, you could call the rojo midge a "variation" of a midge pattern as well. But it still is uniquely different that it is a new fly.
An example of variations would be clousers. Use what you like, any color bucktail, flashabou, tinsel, etc...it's still a clouser but a variation to imitate various baitfish. By substituting materials, you are changing the color, the way it moves, or the way it looks wet but the basic pattern is still tied the same with similar materials.
In the end, it's long and convoluted and not worth the debate. Like others before, if it catches fish, then use it. Call it what you want, heck name it after yourself!
But by definition, it's just a variation...