I've been tying for about 45 years and can't really say that I've seen many "original" flies. There are variations, especially when new materials are discovered, but most of the flies we use today are very similar to the flies used 20, 30, 40 or even 50 years ago. It makes me laugh to see the "new" flies in the many catalogs with a persons name on them, and I've seen something before that was basically the same fly, except maybe they changed some material in it.
I tie most of the flies I use, but will sometimes buy flies I see & like how they look, especially if they're tied by a fellow fly angler. (As opposed to mass produced imported flies!) I have no qualms about copying a fly for my own use either.
I recently bought some flies that I had not seen in awhile. These were advertised in many of the fly fishing & outdoors magazines at one time. I remembered the name, so decided to buy them, and the price was good. I actually bought them more so to collect than to use!
They're mounted on a card in a plastic sleeve & on the card it says the design is registered, with a US trademark number & a copyright number. However, I know I've seen hundreds of flies in catalogs, & listed on various websites that are so similar to these, and with other names on them, yet they could be called the same design.
I would bet a trip to court would not be worthwhile!
I understand "marketing", I tied commercially for 15 years. Tiers want to be recognized for their "creations", because that type of "fame" may lead to bigger & better things, and no one trying to make money tying flies wants to be known as the person who only ties other folks flies. But fact is, most of us do just that!