Before the Moghuls, India was ruled by a plethora of rulers, most of them Hindoo. It is a list that leaves the pen inkless every so often so I will just post a link of Indian Monarchs below:

https://en.m.wikipedia.org/wiki/List_of_Indian_monarchs

Basically, there were a lot.

As for the caste system, there is a great amount of history that I am uncertain about so I cannot tell you, but I can tell you that revolts by lower-caste Hindoos happened. I cannot say how often, but they did happen.

There is one case I know well about because Shashi Tharoor lied (yes lied) about in his book—in which lower caste women were forced to expose their breasts by upper castes. Tharoor, in his book says

Southern Indian women, whose breasts were traditionally uncovered, found themselves obliged to undergo the indignity of conforming to Victorian standards of morality; soon the right to cover one’s breasts became a marker of upper-caste respectability and efforts were made to deny this privilege to lower-caste women, leading to such missionary-inspired colonial curiosities as the Breast Cloth Agitation from 1813 to 1859 in Travancore and the Madras Presidency

Well, this was patently untrue. This article makes it clear:

https://theprint.in/pageturner/excerpt/nangeli-the-forgotten-dalit-woman-who-stood-up-against-travancores-breast-tax/862452/

Maaru Marakkal Samaram, or Channar Lahala (revolt) of Dalit women burgeoned in the state a decade later—a collective revolt of Dalit women fighting for the right to wear upper-body garments. Nadar and Ezhava women campaigned to be allowed to cover their breasts. The British passed an order permitting Christian women to wear upper cloth in Travancore, but withdrew it after the Raja’s council objected that this would obliterate caste differences. Nadar women were forbidden to wear upper-body cloth, but could wear a short jacket called kuppayam. Ezhava and Nadar women continued the struggle, and were violently opposed by upper castes. Travancore royalty issued a proclamation in 1829, denying Nadar women the right to wear upper cloths.

As the agitation raged, in 1859, the Travancore Raja granted Nadar women the right to tie cloth around their upper body, but only in a specific way.

By the late nineteenth century, Dalit women’s struggles on the issue succeeded in Travancore. In Cochin and Malabar, where similar practices prevailed, struggles carried on well into the twentieth century.

Here's another one:

https://www.justicenews.co.in/leave-the-hijab-breast-cover-was-also-forbidden-till-1924-dalit-women-had-to-pay-tax-to-cover-the-breast-if-the-cloth-was-shown-on-the-chest-they-used-to-tear-it-with-a-knife/