This is a brief overview of the creation myth of the Ancient Egyptians as well as the myth of Osiris. The sources do vary and are not consistent with each other; you might have heard the story told a little differently. In some versions, Osiris is the father of Anubis, because Set is sterile (as he is the god of the infertile desert). In some versions, Horus is the sibling of Osiris and Isis, not their son. In some versions, Ra is the first god; in some he is not. There is no internal consistency in mythology that lasted for thousands of years and changed and evolved. I had to pick a version for the sake of the video and run with it.
In the beginning there was darkness, and in the darkness was chaos. Turbulent waters swirled
and covered everything. Then Ra took thought and created himself. Ra saw that there was nothing
but chaos. He created the Benben, the first land, and it rose out of the turbulent waters.
Ra was the sun, and he brought light to the universe. But he was alone. Ra took thought
again and by thinking created Tefnut, the rain, and Shu, the air. These two gods were given the
task of creating order, known as Maat, to balance Ispet, the chaos. Tefnut and Shu fell in love,
and from their union came Jeb, who was the earth, and Nut, who was the sky.
Jeb and Nut were so deeply in love they would not be separated from each other,
but their father Shu pulled them apart and pushed Nut into the heavens so the Maat could be
maintained. Rain fell and plants grew and covered Jeb. Nut and Jeb had their own children, more of
the gods, including Osiris, the god of agriculture, and his wife Isis, goddess of fertility and magic.
They also had Sen, the god of the desert, and his wife Nephthys, goddess of the night.
In time they had their own children. Osiris and Isis had a son named Horus,
while Sen and Nephthys had a son named Anubis. After millennia of ruling the cosmos, Ra began
to be old. He retired to his son Bark. His final act as king was to leave the throne to Osiris.
The land and people prospered under Osiris for he was wise and good. He taught humans how to grow
grain, bake bread, and brew beer. He also taught them about poetry, music, and art. But Sen grew
jealous of his brother and conspired to kill him so that he might rule. Sen managed to trick Osiris
and murdered him, cutting his brother's body into many pieces and spreading them across the world.
Isis took Horus and fled, fearing a similar fate. She started a quest to look for the pieces of
Osiris. Slowly she managed to find all the pieces and to reassemble them. With the help of her
sister Nephthys, Isis used her magic to resurrect Osiris. However, because he had died, Osiris could
no longer stay in the mortal world and became the god of the dead. Horus, the son of Osiris and Isis,
challenged his uncle Sen for the right to rule the kingdom. Through a series of contests and
battles, Horus defeated Sen and restored Ma'at to the cosmos. The cast of characters becomes
especially important when looking at ancient Egyptian art. The family of Osiris is particularly
important in funerary texts, including copies of the Book of the Dead. Judgment scenes become common
in the New Kingdom, in which the dead are depicted entering the throne room of Osiris
to be judged for the deeds of their life. They are led to the room by Anubis. Their heart is placed
by him on a scale. He weighs it against the feather of Ma'at. The heart has to balance cosmic order.
If it does not balance, the heart is cast to Ammit, the Devourer, who is part crocodile,
part leopard, and part hippo. If Ammit consumes the heart, the person loses a piece of their soul
and ceases to exist. However, if balance is achieved, their name is recorded by Thoth,
the god of wisdom, and the person is led forward to be received by Osiris, Isis, and Nephthys to
inherit their eternal reward.