It's odd that you would bring up the Massai without mentioning that their average lifespan for both men and women is in the mid 40's
https://vamosbitchachos.com/maasai-tribe-tanzania/#:~:text=Maasai%20Diet&text=As%20a%20result%2C%20most%20of,the%20age%20of%20just%2044.
It's also odd that you didn't mention that the obvious fact that the diet of these tribes is largely driven by what's available in their environment.
I'm sure if you gave them access to Trader Joe's some of them would likely add blue berries, coffee ice cream and beer to their diet
Have you started adding blood to your diet yet?
No, not odd at all. You asked why milk and honey, and is it because it's mentioned in the bible?
I answered with these examples to show that it has nothing to do with the Bible, and that some people believe consuming milk and honey is fine if these tribes have been consuming them for generations and not only have survived, but the adults are in good health despite their short average life span.
Some argue the Massai have an average short life span because of limited access to healthcare, and basically because of a low level of wealth. Same reason why the Inuit, although very healthy, have an average short life span. Wealth is correlated with longevity.
There is a lot of debate regarding nutrition and longevity. Hong Kong has both the longest life span in the world and the highest meat consumption in the world.
India has both one of the shortest life spans in the world and the lowest meat consumption in the world.
Vegans and vegetarians argue the reason is because Hong Kong is very wealthy, while India is very poor. Is that why? I don't know. I'm sure it's more complicated than that and there are many factors to consider, including quality of social connections.