Did the Emperor want to be a god? No.
The notion about the Emperor wanting to be a god and not caring about humanity comes from the mouth of Erebus in False Gods. Erebus said that while disguised as Sejanus to manipulate Horus into joining Chaos. Chaos, let alone Erebus, is not known for honesty when manipulating pawns. And whats more, Magnus was there telling Horus not to listen to Erebus, and Horus said he knew it was not Sejanus, and even mused that Erebus likely cooked it all up.
So no, the Emperor does not want to be a god.