> Violins are basically ancient and evolved gradually over huge time spans,

Hey! I understand your point and you are completely right about violins and saxophones being completely different, but it is simply not right to use the word "ancient" with violins.

We know pretty much exactly how and when the violin evolved. If you found a viola or another instrument from the 1500s you would perhaps say that it's violin-like, but it's clearly not a violin. The Stradivarius is from the 1600s, the modern concert form is from the 1800s. Any which way it is far from being ancient.

A better example of ancient instruments is the flute and the drum. They are truly ancient, have existed in many cultures, and we do not know when they were first built.

Either way if it's functional then at most you get 20 years of protection. What's shared in both cases is that you can't trademark the shape.