It seems to me that indigenous Americans would have been completely capable of producing their own alcohol before 1492 due to having their own sources of sugar. The most abundant and widespread would be to sprout and malt maize kernels and use that to ferment alcohol similar to making beer. The same goes for sprouting amaranth along with other sources like fruits or honey.
No, that is a myth, there are many varieties of alcoholic beverages that indigenous peoples brewed and consumed in the pre-columbian Americas. These were made from various fruits (e.g. tepache from pineapple, pulque from maguey), honey (balche), sap (from the saguaro, agave, maple trees, etc.), or starchy mashes (e.g. Chicha, Tejuino).
This is fairly similar to the spectrum of things in the old world in ancient times during the stone or bronze ages. Mostly beers and wines with fairly low ABV (below about 15%, typically well below). At the time of the Columbian exchange the Old World had slightly more intensive and productive agriculture and was able to dedicate a greater portion of production towards booze making. And, of course, the Old World had something the New did not: distillation. By the 16th century distillation of alcohol had become fairly commonplace across Europe, with many different regional variants (grappa, gin, vodka, whisky, brandy, etc.) already having attained popularity. Such distilled spirits have around 20-50% ABV, and produce intoxicating effects much easier than weak beers or wines.
The sudden widespread availability of distilled liquors (and even wine) was the novelty, not the availability of alcohol at all. Becoming intoxicated in the pre-Columbian Americas would have required an enormous investment of resources and so was not commonplace at all.
There's always room for discussion, but perhaps the section Party Like It's 1491 (Substances and Recreation) from our FAQ will answer your inquiry.