Isn't it more 'let's store this surplus' - then 'oh man it looks and smells different now but somehow better'.

For example cheese was likely discovered when people tried transporting milk in water carrying bags made from sheep stomachs. While carrying water in them would be fine, putting milk in there for a couple of unrefrigerated days would lead to cheese from the rennet in sheep's stomach that would stay on in the vessel, even after it has been cleaned and even dried.

Same with wine - let's store some fruit juices - it is pretty hard NOT to make wine unless you know about pasteurisation, and even if you do boil it, there are so many natural yeasts just ready to make wine.

Grains that get wet actively want to produce beer :)

Wholemeal flour is chock full of wild yeasts, and wants to become a sourdough starter if you just give it a little water and time.