From the Vedic history of creation we can understand that the first living creature was Lord Brahma, who created the seven great sages and other Prajapatis to increase the universal population
SB Canto 4
The city of King Purañjana was overcome by the Gandharva and Yavana soldiers, and although the King had no desire to leave the city, he was circumstantially forced to do so, for it was smashed by Kālakanyā.
The living entity, separated from the association of the Supreme Personality of Godhead, tries to enjoy this material world. He is given a chance to enjoy it in a particular type of body, beginning with the body of a Brahmā down to that of the microbe. From the Vedic history of creation we can understand that the first living creature was Lord Brahmā, who created the seven great sages and other Prajāpatis to increase the universal population. Thus every living entity, according to karma, his past desires and activities, gets a particular type of body, from that of Brahmā to that of a microbe or germ in stool. Due to long association with a particular type of material body and also due to the grace of Kālakanyā and her māyā, one becomes overly attached to a material body, although it is the abode of pain. Even if one tries to separate a worm from stool, the worm will be unwilling to leave. It will return to the stool. Similarly, a hog generally lives in a very filthy state, eating stool, but if one tries to separate it from its condition and give it a nice place, the hog will be unwilling. In this way if we study each and every living entity, we will find that he will defy offers of a more comfortable position. Although King Purañjana was attacked from all sides, he was unwilling to leave the city. In other words, the living entity—whatever his condition—does not want to give up the body. But he will be forced to give it up because, after all, this material body cannot exist forever.
The living entity wishes to enjoy the material world in different ways, and therefore by nature's law he is allowed to transmigrate from one body to another, exactly as a person transmigrates from the body of an infant to a child to a boy to a youth to a man. This process is constantly going on. At the last stage, when the gross body becomes old and invalid, the living entity is reluctant to give it up, despite the fact that it is no longer usable. Although material existence and the material body are not comfortable, why does the living entity not want to leave? As soon as one gets a material body, he has to work very hard to maintain it. He may engage in different fields of activity, but whatever the case, everyone has to work very hard to maintain the material body. Unfortunately, society has no information of the soul's transmigration. Because the living entity does not hope to enter the spiritual kingdom of eternal life, bliss and knowledge, he wants to stick to his present body, even though it may be useless. Consequently, the greatest welfare activity in this material world is the furthering of the Kṛṣṇa consciousness movement.
This movement is giving human society information about the kingdom of God. There is God, there is Kṛṣṇa, and everyone can return to God and live eternally in bliss and knowledge. A Kṛṣṇa conscious person is not afraid of giving up the body because his position is always eternal. A Kṛṣṇa conscious person engages in the transcendental loving service of the Lord eternally; therefore as long as he lives within the body, he is happy to engage in the loving service of the Lord, and when he gives up the body, he is also permanently situated in the service of the Lord. The saintly devotees are always free and liberated, whereas the karmīs, who have no knowledge of spiritual life or the transcendental loving service of the Lord, are very much afraid of giving up the rotten material body.