[mdp2021]

> That still does not make Sanskrit an ancestor language of English

You are taking 'ancestor' in a strict technical sense, which was clearly not my intention.

> though both English and Sanskrit do share a common ancestry several thousand years ago

And those roots can be found and recognized in the subsequent languages, and there lies the value.

[ben_w]

> You are taking 'ancestor' in a strict technical sense, which was clearly not my intention.

Blutly, this was not obvious, and what you suggested would have been equally true if you'd said:

  Learn Lithuanian. You were writing in a descendant language just now. If you learnt the roots, you would understand the descendants better.

Because Lithuanian has about as much in common with PIE as Sanskrit does.

[nkrisc]

That wasn’t clear to me. Yes, they share similar roots because they have a common ancestor language. Just like any pair of extinct or extant languages descended from PIE.

[messe]

> which was clearly not my intention.

You did not express that clearly enough then.

[mdp2021]

My bad :)

It's just that I cannot allocate the safest amount of effort in composing. I thought it was clear enough.

[schoen]

It is basically confusing an uncle with a grandfather, or an aunt with a grandmother.

These languages are indeed relatives, literally part of the same family, but we usually distinguish whether they are lineal ancestors or not. If you said "Julia is your grandmother" when Julia was actually the person's aunt, that person might get very confused about your claim!

People's aunts do often have a cultural effect on them, but we can still be more specific and distinguish them from their grandmothers.

[hn_throwaway_99]

Except the rest of your arguments fall apart if your point is just "Sanskrit and English shared a common ancestor thousands of years ago and English (and some actual ancestor languages to English) pulled in some Sanskrit loan words". As other commenters mentioned, lots of languages (and languages with long and robust literary traditions) fit this bill, so from an English speaker's perspective there is nothing special about studying Sanskrit. If anything there are a host of more direct ancestors.