If humans branched from apes, then what did apes branch from?
The Great Apes is taxonomically classified as the family
Hominidae, and contains four genera:
Pongo,
Gorilla,
Pan, and
Homo. In other words, the 'great ape' branch has four branches: Orang-outangs are on the first branch, Gorillas on the second, chimps on the third, and humans on the fourth.
The 'great ape' branch, in turn, exists on the 'ape' branch (the superfamily
Hominoidea), which in turn exists as a branch on the 'catarrhine primates' branch (parvorder
Catarrhini), which in turn exists as a branch on the 'simian' branch (infraorder
Simiiformes), etc.
So there was the original Simian, which split into a number of species, one being the Catarrhines. The Catarrhines split into a number of species, one being the Hominoids. The Hominoids split into a number of species, one being the Hominids. The Hominids split into a number of species, one being the Homos. The Homos split into a number of species, one being us,
Homo sapiens.