Hestia, Hera and Demeter are the first three gods ever born (before them were the titans and primordial spirits like Chaos). Their parents are Chronus (a titan, the lord of time) and Rhea (Chronus’ sister, a titan, known as the Great Mother). Hestia was born first and is the goddess of home and hearth, and decided to never get married and be a virgin forever. It is thought that she had a throne on Olympus and that she gave it up when Dionysus came along.
Demeter was born second. Demeter is goddess of the harvest, sacred law, fertility, agriculture. She rides a carriage pulled by dragons and wields a golden scythe. She is the mother of Persephone (non consensual in snake form with Zeus, her brother. It’s pretty messed up.) She also decided to never get married like Hestia, but without the virgin forever thing. Demeter also had a kid (non consensually) with Poseidon in horse form, and that son was Centaurus, who fell in love with a horse and the child became the first Centaur.
Hera was born third. Before Aphrodite came along she was known as the most beautiful goddess, and her eyes were described to be big and brown like oxes. She was tough and selective about the men who liked her. Eventually Zeus manipulated her into marrying him, and she was kind of okay with that because she wanted to be Queen of the Universe anyhow. So Hera is Queen of the Gods, and goddess of marriage, women and childbirth. Her flower is a lily and her sacred animals are the peacock and the cow. Hera, unlike every god ever, has never cheated on her spouse. Hera also sponsored Heracles (hence his name). She has three kids, Ares, god of war, Eileithyia, goddess of childbirth, and her final kid Hephaestus, god of the forge, which she had on her own when she was mad at Zeus for bragging about giving birth to Athena on his own.