Why is the topic of omniscience relevant in Indian philosophy? Because of at least two concurring reasons. On the one hand, for schools like Buddhism and Jainism, it is a question of religious authority. Ascribing omniscience to the founders of the school was a way to ground the validity of their teachings. Slightly similar is the situation of theistic schools ascribing omniscience to God, as a way to ground His ability to organise the world in the best possible way. On the other hand, for other schools the idea of omniscience was initially connected with the result of yogic or other ascetic practices. In this sense, omniscience was conceptually not different from aṇimā `the faculty to become as small as an atom’ and other special powers.
Is Indian Philosophy “caste-ish”? Yes and no, in the sense that each philosophy is also the result of its sociological milieu, but it is not only that.
Is Indian Philosophy only focused on “the Self”? Surely not.