For a moment let's ignore the meaning of "widely propagated".
Apple trees were the first trees to be cultivated. Their genetic diversity is incredible, with for example 2000 varieties allegedly found in Italy only. Other sources report that there are 7000 known apple varieties in the world.
I do not report the sources as I have serious doubts about methods and accuracy, including e.g. the difficulty to catalogue local varieties with limited diffusion. As an example of what I do mean, in my hometown we grow an apple tree which gives pale yellow fruits, with (apparently) random portions having white skin and transparent pulp. Despite such distinctive characteristics and extended efforts on my behalf, I can't find this apple in any study/catalogue.
If then one considers that many apple varieties went extinct, especially since the 19th century with the systematic introduction of market oriented cultivars, an exhaustive answer to your question becomes impossible.
If I were less skeptic about the possibility to establish the first green apple, I would say that the Bramley originated at the beginning of the XIX century, and it comes in both green/red and green only. The White Transparent is definitely green, and originated in (allegedly) 1850. Both these varieties are pretty much common, although I must admit less common than the Granny Smith.
The Granny Smith seems however, according to my research, the first green, dessert apple: all the other greenies I've found are cooking varieties.
That said:
- I am skeptic about the possibility to establish the identity of the first green apple
- Long live the Granny Smith Apple
- The "moment" of which in the incipit is still going...