NOTE: 1960 The first oral contraceptive, Enovid, was approved by the US Food and Drug Administration (FDA) as contraception.
ALSO: If there are over a billion people, why do children have to work? One would think that there would be enough adults to do the work.
The population growth in India is well under control. It ws 2.33 in 2016 and inching lower (1.8 for US and 1.62 for China in the same period). Replacement rate is 2.1. But numbers in India will always seem huge because we have large base, some 1350 million, perhaps the largest in the world exceeding that of China. I read some time this week that we are adding a population of New Zealand every year, i.e., some 20 million. Female sterilization is by far the most common method (Wikiedia.
World Development Indicators - Google Public Data Explorer
The first image that you included was of a brick kiln. That is sorry part of Indian labor scene
in some Indian states (not everywhere). Laborers take a loan and have to work to repay it at the kiln. These kilns belong to local strong men\politicians, and with a corrupt police and administration, they escape government scrutiny.
The second image that you have included is of four children just playing with the implements of their parents who are perhaps having their lunch at this time. They are not working.