Amazon.in "Delivering Essentials Only" banner on site

I dont see it. Probably location specific

according to them only food is essential rest is not

even Dmart and other stores shut down product section like clothes / stationary / bulbs / utensils etc

Yes, it is for MH people, only essential services allowed for next 15 days starting today.
I am expecting these rules will be extended for (at least) 30-45 days considering record breaking +ve cases due to 2nd wave of corona.

Stock medicines for at least a month or two ( Treatment for chronic conditions* )
The deliveries could be delayed or the stocks many run-out

Same here for Bangalore. 

But why is Jolochip an Essential?

well playing field needs to be levelled
if shops are forced to close why should ecommerce be allowed

Why users in other states are seeing this banner?

Most probably due to warehouses located in affected states/cities. Now people ordering have to be very careful as you don’t know from which affected warehouse you will get. Go back to 2020 again & say Go corona, Go