gallifreyan

On some levels I agree, on others I strongly disagree.

So, here's what I think. You are absolutely right in thinking there is no "original" music. This is largely a fiction dating back to the romantic era, an maybe partly to the "Sturm & Drang" era in German literature (that's early Goethe & Schiller for you), which has surely influenced cultural perception a great deal.
Anyway, the idea of a composer sitting in his/ her music room and suddenly coming up with brilliant new ideas is largely nonsense. All of the masters have studied thousands and thousands work by other composers and learned from them, developed their ideas in the context of a new style & taste. I don't think music or any cultural product (literature, art, etc) could be done differently. However, I think it would be absolutely wrong to conclude that there were no great composers. Being able to fully develop a certain style, bring it to perfection or even refine & renew is a hell of an accomplishment, regardless of whether you may have copied certain elements of let's say Bach.

For example: There's one part of a piano piece by Beethoven (I can't remember which one right now and I'm too lazy to look it up right now tbh, but if you must know, I might find time to look it up eventually), which actually follows Renaissance style rules, which is ridiculous in a way, because that was certainly not the popular taste at the time. This actually poses a lot of questions: Did he do this on purpose? Did he sit down and think: Today, I am going to compose a piece set to out-dated rules, but make them sound popular? Or was is something that had just been transported through musical history subconsciously?
Whatever it is, it serves to show that no composer is "original" or free from tradition. However, it also shows that they often use this "knowledge of musical tradition" in a very creative way.

As for your theory concerning the music industry. I'm always puzzled why people would view the classical music industry any differently from today's one. It is what it is: An industry. They want to make money, there is no necessity for them to care about the quality of the music as long as there's money in it.
So, I don't think there is any conspiracy about trying to promote "great composers" no matter how good they are.
Has the music industry used certain ideas to make money? Certainly. Has this included marketing the "original music & genius" fiction of the 19th and perhapy even late 18th century? Of course.
I don't understand, though, why that would make the works of Bach, Mozart, Beethoven, Schubert, etc, etc less amazing. And I'm not even saying every single one of their compositions is a master piece, I'm just saying they were extremely talented composers. Now, you may not like Mozart's style, not be a fan of Schubert, but that's just personal taste and not some big, bad industry trying to manipulate you. In fact, the music industry and the reduced costs of music printing at that time helped to get music to a broader audience. Now, the question of a how a change in the audience also changes the medium and its use is a whole other discussion (but one I'd be willing to go into).
You could say: Well, wait a minute. But by wanting to make money, they are trying to manipulate me. Yep, ok. You have a point here. But what's the alternative? Not being able to access many, many works. Would that be preferable?
(And by the way. Through the means of the music industry we are also able to accesss the music of lesser known composers, which are not viewed as great today. So, if you want to turn away from the commonly loved composers and discover new ones, you are more than free to do so).

So, this has been a long post and I want to come to a conclusion and summary Your observations are not wrong and ocassionally even spot on, but I'm a bit doubtful about some of the assumptions that follow. Now, here's something I'd like to discuss with you:
Can you elaborate on those two points, give examples & proof? Just stating them won't do much to explain them sufficiently, let alone convince me.