[qart]

Both Manu and Ambedkar were extremely unreliable relays of anything Vedic. They both had their own agenda for propping up some castes at the expense of another. Consider that the Rig Veda is written in a language that hardly anyone understands, there is no reason to believe Ambedkar could have faithful translated even one sentence of Rig Veda. Currently, the most authoritative source on RV is Jamison & Brereton's translation. I don't have access to it at the moment, but as I recall, there are just passing references to the varnas, shudras, etc.

[dragonsh]

There is a large body of evidence and research available for systemic exploitation based on Jati and varna's and the legitimacy of it claimed through vedas and manusmriti. May be go through wikipedia and other research sites can find an evidence of this system coming from vedic age and than subsequently developed into more repressive schemes. [1] [2]

[1] https://en.wikipedia.org/wiki/Varna_(Hinduism)

[2] https://sci-hub.se/10.1080/00472338085390141

[qart]

Again, Manusmriti is not a vedic source. Mentioning it will only serve as a distraction and weaken your argument. The paper by Dipankar Gupta is junk. It does not cite the specific verse numbers of specific vedas. Apparently, Gupta has a lot to say, but gives the impression that he is simply making up stuff as he goes along.

The Wikipedia article is better. But you will notice the article citing the book I mentioned earlier: 'Stephanie Jamison and Joel Brereton state, "there is no evidence in the Rigveda for an elaborate, much-subdivided and overarching caste system", and "the varna system seems to be embryonic in the Rigveda and, both then and later, a social ideal rather than a social reality"'.

If there is really a "large body of evidence", I am still waiting for something concrete that you would cite, so that I can go look it up, in the Vedas.