Fermented beverages have been around since the hunter/gatherer
days of humanity's ancestors. While males were out looking for
walking protein to eat, females stayed in the vicinity of the
living territory and collected local vegetation to add to the diet.
If it was plentiful, it might be stored in a skull or other
convenient receptacle whereupon local bacteria would get to work on
it and cause it to ferment. The lucky person that got to drink any
liquid that resulted from overextended storage without
refrigeration might get the world's first "buzz".
This, however may not have been the first instance of alcohol
existing. Even today alcohol commonly forms around the bottom of
grain silos if conditions aren't maintained correctly within. I've
seen pigs staggering around from lapping up the liquid draining
from the bottom of a grain silo.
This could very well have happened in nature with a bountiful
crop of berries falling off a bush, fermenting naturally then being
eaten by some hapless animal. So you're very unlikely to get the
name of a "first person" unless you like the name "Unngh!"