I haven't listened to much of it, but isn't it just talking ?
Yeah it's a form of poetry. And not a particularly ambitious one to say the least.
Ah, so every rap song out there is not actually a song?
All lyrics can be considered poetry. Does that mean all music which involves singing is actually just poetry?
No, more the opposite. That is, recitation which does NOT involve singing is poetry.
OK, but there is a difference between the recitation and the genre of music known as rap, isn't there? The rapping itself may not be music, but it is put to music, making a song.
Put another way, if you have a song that is all instrumental, that is music, yes? If someone raps to that song, is it no longer music?
I'm discussing rap as a musical genre, not solely as the vocals involved. Besides, I don't think that all rap vocals are simply recitation with no music to them.

I haven't listened to enough rap to speak too deeply about it, though. It's not a style I enjoy.
The rap is set to "music" only in the sense that it's an extremely stripped-down candy music, there for no other purpose than to fill up the background. And it can't be any more than simplistic candy because then it grabs the listener's attention and you have music. Which they're consciously trying to
avoid.
So simplistic, when I hear it all I can think is "good grief, play something
adult". I think that's part of why I disparage it. Way too façile, way too childishly simplistic, way too unchallenging (except of course for the aforementioned aggression).
So to return back to this:
You may dislike it (and I dislike most rap, myself), but that doesn't mean rap isn't a form of music.
--- seems to me if you're not
reaching for something in the music -- something that isn't readily obvious or expected, if you're making no attempt to expand the basic music structure, if you're in other words not breaking an art sweat (and deliberately avoiding doing so), then it can't count as music.
Simple 12-bar blues is much more a poetry. It too uses a completely predictable music background but offers a
cadence that forces anticipation of the punch line -- and in that there is much art, as well as in the circumlocutionalry delivery of the expression. It's nowhere near the blunt instrument that "rap" is. And of course, the 12-bar blues structure offers endless opportunity for purely musical expression in between with the solos.