Climate change isn't only new record high temperatures. It's also, as described in the article, temperatures consistently being higher than is regular for this time of the year.
This is more or less covered in the article as well:
> Meteorologists from the India Meteorological Department (IMD) found that March 2022 was the hottest March for India as a whole since 1901, with average highs jumping to a staggering 3.35 degrees Fahrenheit (1.86 degrees Celsius) above the climatological average.
Heat waves happen, and have happened before, but if they become more common, longer, hotter on average etc you can see this in the statistics.
As the other comment already pointed out, the study linked in the article [0] makes it clear that it's not the case that 1901 was the hottest March, but instead 1901 is the year that data gathering began. The warmest March on record was 2010.
> Characteristics of Average maximum, minimum and mean temperature for the country as a whole and over four homogenous region during March 2022 and its comparison since 1901
> [...]
> The country averaged monthly mean temperatures of 26.67ºC is the second warmest since 1901 (The warmest year on record was 2010 (26.671 ºC)).
Your observation is correct that for all practical intents and purposes, this March was as hot as the hottest March ever recorded since bookkeeping began in 1901.
This may surprise people, but places near the equator are really god damn hot most of the time and when they have a heat wave it’s even hotter.