This has been nagging at me. I grew up on "Puck of Pooks Hiik" and "Rewards and Fairies" because Mum was from Sussex. He did expect a lot of his child readers.
I've been through various phases of trying to make sense of his complexity, and there's one thing that may cast some light one his attitude to Gunga Din, and to the common soldier as well. Or shadow.
In those children's books he writes of his attitude to the Hobdens, a line of labourers who worked in Burwash time out of mind, in his poem "The Land".

"Hob, what about that River-bit ?" I turn to him again,
With Fabricius and Ogier and William of Warenne.
"Hev it jest as you've a mind to, but"—and here he takes command.
For whoever pays the taxes old Mus' Hobden owns the land.

But, I have it by oral history through my mother, and her school friend from Lewes Grammer (Girls), who had it from her father in Burwash, Mr Garden, that when it came to the Depression, that wasn't how he felt. The girls would have been at that school in the late 20s, early 30s, so at that point it would have been contemporaneous.
The staff at Batemans were suffering from 'cost of living" and asked for a raise in wages, which was refused. I only heard this once, and can't recall if a strike was mooted or took place, but at any rate, Kipling was exceedingly put out, and there was much ill feeling in the village towards him. He may have written respect for the labourer, but did not feel it when it came to supporting him.

Notes for non-Sussex residents. Batemans is the large house in which he came to live, in the village of Burwash Weald, west of Burwash itself, which is north of Hastings.