There was One.
One was a fourth dimensional intelligence. The fourth dimension is consciousness. He didn't know where he began and where he ended, and he didn't really have a gender it's just a convenient pronoun.
There was nothing but One and void. He was alone. Being consciousness, he knew this. He was without language, but being consciousness had thought.
One day, he thought:
"What if I wasn't alone?"
BANG. The Universe happened.