Yes, I'm aware that India is a single country, while Europe wasn't. But with the right amount of autonomy, you end up with the same conditions, and it's not too different in practice.
Also these states (or ancient / medieval kingdoms in them) have rarely been "at war" with each other. Until recently, India was sparsely populated and it was easy the "migrate" to another land to establish your kingdom rather than fight with your brother or cousin.
If you are interested, Francis Fukuyama [1] has a very interesting theory that says that India has been held together by its society and not its state. Multiple waves of invasion have not fundamentally altered the texture of the society, parts of the new culture have been slowly assimilated in it, often forcing the invaders to adapt to their new home.
[1] https://en.wikipedia.org/wiki/The_Origins_of_Political_Order
Though nationalism is on the rise in India, it is still a very fractured society, with a strong emphasis on autonomy of groups to make their own "rules", treating the state as a weak actor. The quality of education at all levels is shockingly poor (specially in science and technology) and no way ready to produce any kind of revolution.
While India will make painfully slow progress in the physical sense (infrastructure), it is very unlikely to follow the Chinese model. Sadly India will remain fractured (or de-centralized, if you want to put a positive spin).
If you have been to India, you will know the pervasiveness of "status quo". Things are so broken, hard and complex that it does not make sense to even start doing something.