> that the Aryans were a nomadic, tribal cow-herding people who didn't tend to live in fixed structures
What are you talking about? Almost the entirety of the Mahābhārata deals with politics, intrigue, war- and state-craft, amongst others. The Rāmāyaṇa discusses an equally complex civilisation. By around ~500 BCE, Northern India had coalesced into large, hierarchical, and complex civilisations and city-states, which conducted war, trade, and diplomacy both within and outside the Indian subcontinent. The Kalinga war was conducted in ~260 BCE, and Alexander the Great halted his advance in India about half a century prior.
There's something about Indian history that is deeply, deeply divisive like almost no other civilisation's history is. On one side, there's the full-on jingoistic and ultranationalistic stuff like the out-of-India theory, that ancient Indian mathematicians and scientists built a civilisation rivalling the 21st century, that Sanskrit is the 'mother of all languages', and that it is a 'programming language' (yes, it has a highly regular, formal, and almost context-free grammar that allows it to be easily parsed like few other natural languages can, but that's it).
On the other hand, there's dismissive, 'Orientalist', and sometimes outright racist views. Yours is a good example of the dismissiveness and Christo-centric/Western-exceptionalism thought process that was the zeitgeist amongst many Western scholars until well into the 20th century. I daresay it is precisely in reaction to this sort of paternalistic dismissiveness that the above-mentioned jingoism sprouted in the first place.