Did human start raising grain for bread or beer?
I think we started making beer. Its got water, carbs, flavor, good bacteria, good fungi and most importantly, alcohol.
its got everything you need to stay alive and feel good about it for 24 hours.
The first grains were used to make an alcoholic beverage of sorts, yes. Historically there was only a few ways to preserve food, fermenting was one of them and quite possibly the healthiest way to preserve food as well.
Of all places, why would you ask this here?
Archaeological evidence points to beer, but archaeological evidence doesn't mean dick thousands of years from when it was made with a perishable product.
Before the development of modern filtration and brewing methods, beer had nothing to do with the beer of today.
Whole families drank beer because it was cheaper to make, it had all the nutrients and low amount of alcohol, it's why you see 'wine' and 'mead' to be popular in history as main alcoholic drinks, rather than beer which was considered as something for the masses.
They had to preserve the food, it wasn't about getting drunk.
I'm sure they tried fermenting pretty much everything, the idea was never to make beer, just to preserve their food.
You know they didn't have fridges or freezers back then, yeah?
Besides, the fermented grains they prepared were far and away nothing like we would call beer I'm sure.