India in 1947 was characterized by very low per capita income. There were a lot of people, so there was always a big GDP, but per capita income was very low.
In some ways India had a fully developed capitalist economy, and it had some of the oldest capitalist institutions in Asia. So there was a modern economy, but it was very thin.
There was a manufacturing sector, but it didn't cover many industries. There was even a steel industry and a relatively strong textile industry, but these were limited.
It was predominantly a subsistence economy. Most of the villages at the time didn't even have road connections. They were connected only by tracks to the outside world. They weren't part of the market economy.
And In the second half of the 1990s one also began seeing the rise of the IT sector.
Two explanations are given for why that sector became so successful:
The first is that the bureaucrats didn't notice what was happening until it had already happened, so they couldn't really interfere and put up a web of regulations and restrictions.
The other is that the government did some things right. Its founding of the Indian Institutes led to a flow of highly qualified manpower, many of whom found vocation in the IT sector. India at long last found its niche in the world economy, which wasn't in exporting manufactures, like the East Asian countries, but instead was in the services sector, and IT in particular.