What you refer to as castes (jati) is incorrect. These four groups are social classes (varnas). To suggest that caste is similar across time and space is a challenging proposition. To equivocate ancient south asia with having the necessary structure for the transglobal 21st century is a nostalgic interpolation in extremis. For example, the rgveda is 10 books which mostly explain why the people who composed these poems and the heroes upon whom the poems focus justify their martial action “yoga” and the complete and utter humiliation and annihilation of their enemies through receiving the support of the God of war Indra and his berserker retinue, the maruts. There are poems describing the metaphorical rape of rivers which the heroes wanted to cross in order to go pillage their enemies during the seasonal period of yoga, which the poets promised to remember in their victory songs as they celebrated with a big bbq of beef, Indra’s favourite, and other intoxicants…such as soma.