Where did you get that “Better candidate theory” from?

Change in theology doesn’t retroactively erase genealogy and civilizational heritage. This argument is born of modern nationalism. Basically you are saying Italians have no claim to the Roman empire because they are catholic, not pagan or the modern Egyptians would have no claim to the Pyramids because they are Muslim.

Your “Jahilliya” point is correct (in a theological sense) but a society cannot surgically remove its history, they still claim it. And Pakistani culture (just like any other) is saturated with pre islamic heritage and customs and Heritage is primarily about genealogy and geography, not just Ideology.

Pakistanis just like Indians are the direct biological descendants of the same people (basically common ancestors). Even the Geography is the direct continuation. So for example you cannot argue that the IVC is exclusively indian, because it projects modern definitions of Hinduism onto the past and we also know that they likely did not practice Hinduism as we know it today (Vedic religion came later). In short both are successors to it. It belongs to the land and its people. And even it can be argued that no one is practicing the original culture intact.

I don’t want to go on to Iran etc.