The truth is a lot more complex than these binary characterisations. All Indian languages have loanwords (tatsama, tadbhava). One interpretation is that Sanskrit is like bones of the linguistic body while other Prakrit languages provide it with muscle and mass. Sanskrit in it’s abstract form is very hard to use conversationally. Finally Hindi which is the dominant language in the north came from Hindustani which itself has heavy influence of Persian/Urdu.

Linguists have abounded these simplistic trees of ancestry a while back. Truth is all these languages interacted and improved one another. For example it’s likely that Dravidian languages were spoken in the Indus Valley civilization. That would make them the greatest ancestor. Sanskrit was formed much later and was likely influenced by it.

Indo Aryan itself is a racially rooted theory started by Europeans to extract familiar parts of Indian culture and define a collective identity. Reality is far more complex