The concept of the musician and the status of the musician in society is culture-specific. Think, for instance, about your own concepts relating to "the heavy metalist", "the folk musician", "the DJ", "the sarangi player", "the female drummer", and so on.
It may also be relevant to mention the songs produced by some animals, including birds. Although many would surely debate whether birds are musicians, their ability to produce variations on the characteristic song of their species is a subject deserving more research (though relating less to music and more to animal communication). The freestyle chatter of even common birds, although lacking the complexity of methods employed by human beings, must be regarded as having some relation to the origins of music. Human beings did not begin producing music by banging away on a keyboard, nor are they the only creatures which respond to (or produce) rhythm and melody.
It should be noted that although in many cases the name of the player is made from the name of the instrument + "ist", it does not work for all instruments. Trumpetist for example is nonsense. There are also widespread differences in the acceptability of some of these terms: for example percussionist is in general and uncontested use whereas violist is not.
The instrumentalist is far from denying the independence of reality, but when this independence signifies anything he considers it a limiting conception, in the same sense that the law of conservation of matter or energy is a limiting conception.
And so while the instrumentalist is a realist, he differs widely from the new or presentative realists, since we have already observed that their reality comes to be a series of unknown entities far removed from actual things.
The instrumentalist is constantly campaigning; his whole method is that of overcoming the autocracy and arrogance of the brute facts of experience, but he can never merely campaign, just for the sake of campaigning.