Tamil is certainly the oldest living language in this world. As pointed out, Sanskrit is neither older nor independent as Tamil. Infact most of the sanskrit words have their roots in Tamil. I present here the evolutionary steps of few sanskrit terms.
Shiva – from “Sivan”- a modified form of “Sivandavan”(one who is red in colour)
Pooja – from “Poo + Sei” (Poo-flower, sei-offer, to offer with flower)
Krishna – karuttanan > kruttanan > krushnan > krishnan > krishna (meaning black in colour)
Indra – Indiran = In + Irai (In-Inbam-joy, Irai – God, God of joy)
Rudra – Udhiram > Urudhiran > Rudhiram > Rudran > Rudra (meaning having the colour of blood)
Thus all these terms have their roots in Tamil.
Sanskrit doesn’t have its own grammer but borrows from prakrit text of Panini.
Sanskrit is the language of latter vedic period and was made glorious in medieval period by false claims due to which Tamil suffered heavily but stood up with time due to its independent evolution and Sanskrit broke into several sister languages
Undoubtedly, Tamil is the oldest living language. Recent archaeological evidence suggest that Tamil could have been the language used by the Indus civilization and even the Sumerians. References to rivers that dried up 10000 years back are seen in Tamil literature. Also, there are references to a lost continent, which is believed to be buried under the Indian ocean. We need more archaeological research in the ocean to get concrete proofs for this. In fact, there is a possibility that Tamil was the root of sanskrit, which is believed to be the root of all Indo European languages. Till date, we can trace almost 60 – 70 % of Sanskrit words to their roots in Tamil.