Try to make something useful that hasn't been invented yet - and you'll see my point.

With this logic, you are simply making argument that those making any pre-required invention is more important than any later invention.

Try making light bulb without glass blowing knowledge. Try making light bulb without electricity. Try making light bulb without food and water.

Of course, you can't make something useful before is is invented. But that doesn't mean the invention must be hold at higher important.

Strawman.

My argument is not that a new invention cannot be based off of or require previous inventions in order to function. My argument is that improving an invention is not possible without the invention existing.

It's like improving upon a camera without cameras existing. The invention of the camera, in my opinion, is more important than the continued improvements of the camera, at least up until digital cameras - which is innovative enough to recapture the concept of photography but improve upon it in many significant ways. [0]

While improving upon an invention has its own worth and merit - I do not typically hold improving something to the same merit as inventing it. Coming from someone who often improves things, but does not create them.

When it is a drastic improvement or an entirely different approach (ie. innovative changes) - those hold a great deal of merit and may be worthy of respect. But being able to market something better is not something I respect.

I do not hold a lot of respect for marketers and advertisers. I see it as an abuse of trust against people by feeding them subtle lies and abusing how impressionable people can be. If you respect good marketers, then we're merely at a disagreement of opinion. I do not respect people who are skilled at manipulating people. While it may certainly take skill, require knowledge, and may even be difficult! It is not deserving of respect, in my opinion.

[0] Or arguably make it worse, depending on your artistic perspective.