[0] https://www.manchester.ac.uk/discover/news/indians-predated-...
But then I checked your link, and in fact it doesn't at all say that Newton's work on calculus wasn't original. The thing it claims Keralan mathematicians might have done first was infinite series. So I can downvote you for pre-emptive complaining about downvotes with a clear conscience :-).
But then I checked (so far as I easily could using Amazon's "look inside" feature) the book referenced there, and in fact it does mention that a guy called Bhaskaracharya had something like the notion of derivative a couple of centuries before Newton and Leibniz. (It looks to me as if what he had was a special case rather than the general concept, though; if I'm right about that, it's an important distinction.) So now I'm conflicted again.
[EDITED to add:] The book in question is called "The crest of the peacock: Non-European roots of mathematics".
Well, it seems to me that the most that can credibly be true here is that Newton's discovery of calculus was influenced by closely related prior work by the likes of Bhaskaracharya. I don't think this is enough grounds for saying that "Newton most likely didn't invent Calculus". So, downvote it is. (For complaining about getting downvoted, not for the hyperbole about Newton.)
So, no downvote here, but what's the point? Even if someone had previously invented the Calculus at some point in ancient history, they didn't do anything noteworthy with it, and/or, some catastrophe erased the evidence of their work. Does this in any way diminish Newton's invention?