Is Music Melody, or Is It The Other Way Around?

Is a melody as strong of a building block as a sentence or an image? A sentence is able to convey a thought or an action. An image preserves a moment, which in turn allows for some sort of understanding (not that it must, but that it is able to). What does a melody do? It stays in our heads for some unknown reason, but what is it?

It is not composed of words with meanings to combine to a thought as a sentence is. A melody is merely a set of tones played in a specific order with specific durations and accents. There are those that would argue that melody conveys emotion. Major = happy, delightful. Minor = sad, depressed. But there is nothing of substance to lead to that; it is merely our reaction to sound. (And that reaction in itself may just be trained in us culturally. Maybe if, from childhood, we were shown happy images alongside minor melodies and horrifically depressing images alongside major melodies, we would have a different perspective on the meaning of a melody, or rather, what emotion a melody conveys.)

I guess my point is that melody, as a building block for music, does not seem to be as strong of a basis as say a sentence for literature or an image for a painting or a photograph or a film. Music, in itself, seems to have less of a logical reason to exist as an artform if melody is its only reason for existing.

This leads to my point of writing all of this: I hate when someone says that something is not musical because it lacks a melody. A melody, as I see it, is only a small part of the artform of music. Music is an artform composed of sound. A melody is a happy coincidence of putting the right notes in the right order and then...well there it is, a singable tune. But what about the beauty of the scrapes and scratches and noises of everyday life? of the sustained chords that seem that they'll never end, taking on a whole new life just through the fact of their duration? These are the things I love to hear used in music. And, well, defining when they are sounded together correctly that is up to the listener.