There are many stories of these giants based from the claims of some American Indian tribes, to stories from the "Book of Enoch". But before we dive into this subject, we have to know and understand who the sage "Kashyapa" is, and how he is called "the progenitor" of the Earth.
Now, here in the Wiki states this: "Kashyapa (IAST: Kaśyapa) is a revered Vedic sage of Hinduism. He is one of the Saptarishis, the seven ancient sages of the Rigveda, as well as numerous other Sanskrit texts and Indian mythologies. He is the most ancient Rishi listed in the colophon verse in the Brihadaranyaka Upanishad.....Kaśyapa, alternatively kacchapa, means "turtle" in Sanskrit. According to Michael Witzel, it is related to Avestan kasiiapa, Sogdian kyšph, New Persian kašaf, kaš(a)p which mean "tortoise", after which Kashaf Rūd or a river in Turkmenistan and Khorasan is named. Other relations include to Tokarian B kaccāp ("brainpan"), Polish kacap ("brainpan", "hardliner"), Tokarian A kāccap ("turtle", "tortoise"). Frits Staal agrees that Kaśyapa means tortoise but believes that it is a non-Indo-European word." He would be one of the Rishis that was saved with King Manu, to be on the boat being led by Vishnu's avatar Matsya (Fish Form, as Dagon). "Kashyapa is mentioned in numerous Hindu texts such as the Puranas and the Hindu Epics. These stories are widely inconsistent, and many are considered allegorical. For example, in the Ramayana, he is married to the eight daughters of Daksha, while in the Mahabharata and Vishnu Purana he is described as married to thirteen daughters. Some of the names of the thirteen daughters Kashyapa married in the Hindu text Vishnu Purana are different than the list found in Mahabharata. Some texts describe him as son of Marichi and a descendant of the solar dynasty, others as a descendant of Uttamapada who married Daksha's daughters, and yet others relate Kashyapa as a descendant of Hiranya Kashyapa. These texts may correspond to different characters, all named Kashyapa."
(Daksha is the god that had his head cut off by one of Shiva's demons called "Bhairava", and then replaced with the head of a goat. He had indirectly got his daughter killed, because she was with Shiva with whom he had disapproved)
The Puranas and the Epics of Indian tradition mention Kashyapa and his genealogy numerous times. These are inconsistent, with allegorical stories exalting him as the father of all gods, men, demons and empirical universe, in some conflated as the Kurma avatar of the Hindu god Vishnu. In the Vishnu Purana, Kashyapa marries thirteen daughters of Daksha: Aditi, Diti, Kadru, Danu, Arishta, Surasa, Surabhi, Vinata, Tamra, Krodhavasha, Ira, Vishva and Muni. Kashyapa, in the Vishnu Purana and Vayu Purana, is attributed to be the father of the Devas, Asuras, Yakshas, Dravidas and all living creatures with various daughters of Daksha."
"He married Aditi, with whom he fathered Surya or alternatively Agni, the Adityas, and in two inconsistent versions Vamana, an avatar of Vishnu, is the child of Aditi and Kashyapa. In these fables, Kashyapa is the brother-in-law of Dharma and Adharma, both of whom are also described as married to other daughters of Daksha."
"After the famous Samudra Manthan (the churning of the ocean), when the devas and asuras churned the ocean and got the amrit pan (nectar/pot of immortality), Lord Vishnu’s Mohini Avatar took the pot and made the devas drink the nectar, leaving the asuras empty. Feeling the circumstances to be unfair, Diti, the mother of asuras, asked her husband Sage Kashyapa to bestow her with great sons that will ruin the devas. Sage Kashyapa, as a righteous husband agreed to this and gave Diti two sons, Hiranyaksha and Hiranyakashipu. Both sons were mighty and defeated the devas. Hiranyaksha was however killed by Varaha Avatar of Lord Vishnu, because he trapped Bhūmi Devi (Goddess Earth) in the cosmic ocean."
"Hiranyakashipu took over the world and stopped the worship of gods, and established himself as a god. He was killed by Narsimha Avatar of Lord Vishnu, when he tried to kill his own son, Prahlad, when he found that Prahlad became a devotee of Lord Vishnu. Diti was more furious, but she could not wish to harm Lord Vishnu as he is a member of the Tridev and planned to kill Indra, the king of devas. She went to Sage Kashyapa again and demanded a son that would kill Indra (since he was the one who requested the Tridev to help). Sage Kashyapa impregnated her with a son that would kill Indra, but also told that it is only possible if she does ritualistic ceremonies to Lord Vishnu everyday. Diti did that and she did the rituals everyday."
"One day, she became tired and fell asleep after the ritual, forgetting to wash her feet before sleeping. This made her womb vulnerable, and Indra took a tiny form and entered her womb, and using his weapons he cut the foetus into 49 pieces. These 49 pieces were later known as the Maruts. Due to the rituals she performed, the evil thought of killing Indra went away and she did rituals daily."
From his wife Aditi: "Aditi (Sanskrit: अदिति = "limitless" or "boundless”) is a Vedic goddess in Hinduism, the personification of the infinite. She is the goddess of the earth, sky, unconsciousness, the past, the future and fertility. She is the mother of the celestial deities the Adityas, and is referred to as the mother of many gods. As celestial mother of every existing form and being, the synthesis of all things, she is associated with space (akasa) and with mystic speech (Vāc). She may be seen as a feminized form of Brahma and associated with the primal substance (mulaprakriti) in Vedanta.....Aditi is a daughter of Daksha and Panchajani. The Puranas, such as the Shiva Purana and the Bhagavata Purana, suggest that Daksha married all of his daughters off to different people, including Aditi and 12 others to Kashyapa rishi. When Kashyapa was living with Aditi and Diti in his ashrama, he was really pleased with Aditi’s services and told her to ask for a boon. Aditi prayed for one ideal son. Accordingly, Indra was born. Aditi. Later, Aditi gave birth to others, namely Varuna, Parjanya, Mitra, Amsa, Pusan, Dhatri, Tvastra, Aryaman, Surya, and Bhaga."
(The 12 gods are the 12 tribes in this perspective)
From Diti: "In Hinduism, Diti (Sanskrit: दिति) is the Mother of Demons and supporter of Demonic attributes. She is mother of both the Marutas and the Asuras (Daityas) with the sage Kashyapa. She is said to have wanted to have a son who would be more powerful than Indra. She is said to have killed her previous children because they tried to murder her. Diti used black magic to keep herself pregnant for one year."
"Indra used a thunderbolt to splinter the fetus into many pieces, from which originated the Marutas. Diti is one among a group of sixty daughters of Dakṣa and Panchajani. Her sisters included Aditi and Satī, among many more. She is one of the thirteen wives of the sage Kashyapa. Her two most famous sons were Hiraṇyakaśipu and Hiraṇyākṣa, who were the gatekeepers of Lord Vishnu at Vaikunta & who are said to have failed to keep their dharma and were slain by Vishnu in subsequent rebirths until they went back as the gatekeepers Jaya and Vijaya. Diti also had a daughter named Holikā. She is usually depicted as being cruel to both her husband Kashyapa and her sister Aditi. She is obsessed with trying to bring the Asuras into power. She is a bitter enemy of Aditi's sons, the gods, and she was instrumental in gaining control and autonomy over them."
From Kadru: "In Hindu scriptures, Kadru (Kadrū) is usually regarded as the daughter of Daksha. Kashyapa married Kadru and twelve of Daksha's other daughters. Kashyapa was the son of Marichi, who was the manasputra or mind-born (spiritual) son of Brahma. Kadru was the mother of a thousand nāgas."
From Vinata: "According to Hindu legends, Vinata is the mother of birds. She is one of the thirteen daughters of Prajapati Daksha. Married to Kashyapa along with her 12 sisters. She bore him two sons, named Aruṇá, and Garuda (Suparna)." From Surasa: "In the Hindu epic Ramayana, Surasa is one of the 12 daughters of Daksha, who are married to the sage Kashyapa. She became the mother of the nagas (a class of serpents), while her co-wife and sister Kadru gave birth to uragas, another class of snakes. Vasuki, Takshaka, Airavata and other sons of Surasa are described to live in Bhogavati."
Below is the battle between Hanuman the monkey god and Surasa who is said to be the mother of serpents. Here Surasa is depicted as a black woman whereas other paintings show her to be in monstrous form.