Have you looked at Malayalam, Tamil etc and even Hindi?
Did these languages suddenly develop a close similarity to Sanksrit when there have been no conversational Sanksrit around for 800 years or so?Do you even know Sankrit to reference some Wikipedia article?
No. But Hindi and Malayalam are later languages. Hindi is a medieval language. How is that relevant to this issue? Here we are discussing if Sanskrit had its origins in India or has it descended from a foreign ancestor. Sanskrit may have spawned several modern languages, but what spawned Sanskrit? Answering that question will answer the question of origins of vedic civilization.
As for Tamil, it may have borrowed words from Sanskrit, which is obvious for coexisting languages, but Tamil is certainly not a descendent of Sanskrit.