How did isis become a goddess?

Isis is one of the four gods and goddesses born to the goddes Nut, of the sky, and god Geb, of the Earth. She was born a goddess, and married her brother Osiris. When Osiris was killed by their brother, Seth, she re-constructed him, but he was still stuck in the underworld, where he is King. Isis is one of the most well-known symbols for motherhood and protection.