All histories are taken account only on the basis of writings of a period, sculptures and architectural works of that era. If u have any doubts on how people write history, Go and ask a Historian.
So taking account of the work of Ramayana and mahabharatha, they are authentic proof for the existence of Rama. Morover we have various places associated with him all over the country and anecdotes by various scholars. that is proof enough. Moreover, ramayana and Mahabharatha, by themselves in many places advocate proofs for the existence of the charecters.
if u read the epics u will know better. The castisim preached there is only about the way of life and the work being performed by them. You cannot find many brahmins in these texts in major roles, except maybe for Dhrona in the Mahabharath, who was also later considered an outcast as he fought against his principle of Peace. read and Learn, there are a lot of proof lying around you for The existence of the Lord Rama.
lastly, If Kamban, Kannagi, AOwvaiyayar, Valluvar and many other scholars you praise are true, then valmiki from whom kamban got inspired was also true and thus Very True is Rama. for your information, the caste politics just came after 1650's when British wanted to divide the people. refer your History till then. there was no mention of caste problems. The politicians now are just following the british for monetary gains.
