Although the exact origination of the term "hip hop" is and will always be unclear, it existed as a term before it was a music.
It's pretty well established that DJs at street parties in the Bronx and Upper Manhattan invented the practice of using two turntables and two copies of the same song, to play the drum/bass break that was usually present in extended dance remixes of funk or disco records.
There were dancers, or b-boys (break boys) who were known for doing athletic dance moves to these very rhythm-heavy portions of the songs.
The DJs would alternate from one turntable to the other, playing and replaying the drum breaks of the records over and over again so the b-boys could dance continuously to their favorite portion of the song.
Their dance moves were called "break dancing" or "top rocking" or "up rocking" or "hip hopping." There were various dance crews, each of whom came up with their own names for the style of dancing they were doing, so there were a lot of different names for the kind of dancing done to breaks.
During these repeated breaks the party organizers (MCs) would often make comments about the dancers and their skills, make announcements, etc. That was the beginning of rapping.
In the earliest rap songs there are plenty of references to dancing, breaking and hip hop, thus the nonsense patter on songs like "Rapper's Delight": "the hip, the hop, the hip hip hop you don't stop rocking bang bang the boogie to the rhythm of the boogie, the beat." This sounds like what it probably originated as - an MC at a party encouraging the dancers.
The first tracks used for rapping were called "break records" or "break beats."
So to me it seems that hip hop begins as a style of funk/disco dancing that created its own subgenre of music performance - i.e. playing break beats on two turntables.
The lack of melody inherent in playing break beats over and over lent itself to spoken, not sung, vocals.
So hip hop dancing lead to hip hop music (DJing) which led to hip hop vocals (MCing).
That's my view.
That makes too much sense.