What is the main purpose of the Purusha sukta in ancient Indian society?

To justify the social hierarchy and divisions

The Brahmanas, in order to justify their claims, frequently relied on a hymn from the Rigveda called the Purusha sukta. This hymn depicts the sacrificial offering of Purusha, the primaeval man, from whose body, it is believed, all elements of the universe and the four social categories originated. According to this sacred text, the Brahmanas were said to have come from Purusha's mouth, symbolizing their role as priests and custodians of knowledge. The Kshatriyas were believed to have been born from his arms, representing their duty as warriors and protectors of society. The Vaishyas were said to have emanated from his thighs, signifying their responsibility as merchants and agriculturalists. Lastly, the Shudras were thought to have originated from his feet, reflecting their role as labourers and serving the other three varnas. By citing the Purusha sukta, the Brahmanas sought to establish a divine basis for the social order, reinforcing their own elevated position in the hierarchy while perpetuating the prevailing social structure.