Because the god that the ancient egyptians belived their king to be - Horus - his first throne was his mothers - Isis - lap. (Like when he was a baby)
Isis was an Egyptian God therefore worshiped by many
The ancient Egyptians.
Egyptians had many gods eg. Isis, Hathor, Osiris, Anubis etc.
The ancient Egyptian gods such as Isis, Osiris, Horus, Ra, Hathor, and Bast.
Goddesses of ancient Egypt include Isis, Ma'at, and Seshat.
Isis was the Egyptian goddess of women, mothers, children, magic, medicine, and the Ritual of Life. So her importance can not be disputed.
Isis was the Goddess of Fertility and the husband of Osiris. Without Isis, there would be no Osiris, so no Osiris, No Agriculture, No getting into the Underworld, you know, the things they care about.
A throne is the symbol of Isis because she wore it as her headdress and as a crown to.
Simply because she was a GOD and all gods had to be worshiped, honored, and respected by the ancient Egyptian people.
Isis wore a red dress with a throne on her head.
Isis, King Tut and Cleopatra
She was the first to have an immaculate conception.