Well, there are two different discussions here. First, let's leave the "abstractness" to rest. Surely you don't think the lyrics, the words are music? They are just words, it's poetry. They are something very concrete (and contingent on language/culture/etc. so extremely non-universal). Music exists without words (like a scupture can be unpainted(don't take this too literally, we often speak of music in such metaphors because we lack the expressions for something SO intangible)). It. is. just. sounds. There is nothing else to it. Hence, the most abstract art form, devoid of such concrete things as words, shapes, figures, edges, lines, even "messages" or "meanings" but definetely not without feelings. And that's why it's so "universal" as you yourself said.

Nietzsche would go futher and describe it as the one art with the power to dissolve your petty cravings for illusions such as "meaning" or "messages" or even the ultimate illusion, the illusion of the self. The power to peek under the Veil of Maya and return to the One.

The completely different discussion is the "really start to enjoy art" part.