"आत्मा को कुनै जात हुदैन !" - It is axiomatic. I don't think we need to invoke religion, spirituality or even science in order to prove it. In absence of any evidence of existence of "आत्मा " - one can only argue, using same non-sense, that it has a caste !
However, we do know some humans are classified based on a caste system, to be specific only humans following "Hindu" religion ! Important question to ask here is not why, but how ?
Ujl you've tried to explain this and stated "There is no place for caste in Vedic Sanatan Dharma", then how come caste system evolved in this particular society? What motivated the need for such hierarchy ? If we now know this was ill-practice by some idiots in the past, why aren't we correcting it ? Is it fair to say, there is a disconnect between vedic facts and practice?
As I see it as an interesting topic - "why do we have a caste system even though our Ved and scripts doesn't state such ?", I would like learn more.