After all how did Sheshnag originate on earth

In the Hindu religious texts, there is mention of various serpents such as Sheshnag, Vasuki Nag, Takshak Nag, Karkotak Nag, Dhritarashtra Nag, Kaliya Nag, etc. The story related to Sheshnag dates back to the primordial times of the Earth. The origin of the Nagas is linked to Kadru and Vinata, the daughters of Daksha Prajapati, both of whom were married to the sage Kashyapa. Once, Sage Kashyapa, being pleased, asked his wives to wish for a boon. Kadru asked for the boon of becoming the mother of a thousand powerful serpents, while Vinata only asked for two sons. However, Vinata told Sage Kashyapa that her two sons would be more powerful, heroic, and handsome than Kadru’s sons. Kadru gave birth to a thousand eggs, while Vinata laid only two. In due course, from Kadru’s eggs emerged a thousand serpents. The Puranas extensively describe various Nagas, especially Vasuki, Shesh, Padma, Kambal, Karkotak, Nageshwar, Dhritarashtra, Shankhpal, Kalakhya, Takshak, Pingal, and Mahanag.​

Among Kadru’s sons, the most valiant was Sheshnaga, also known as Anant. Upon witnessing that his mother and brothers had deceived Vinata, Sheshnaga abandoned them and began penance on Mount Gandhamadan. Pleased with his devotion, Brahma Ji granted him the boon that his intellect would never deviate from righteousness. ​Brahma Ji also told Sheshnaga that the Earth, along with its mountains and rivers, is constantly moving. Therefore, he should support it on his hood to stabilize it. ​ By the grace of Brahmaji, Sheshnag held the entire earth on his hood. Let us tell you that Lord Vishnu sits on the seat of Sheshnag in Kshirsagar. According to Hindu religious texts, Lord Shri Ram’s younger brother Laxman and Shri Krishna’s elder brother Balram were both incarnations of Sheshnag.