I don't think alcohol would work well for embalming, unless it's that Isopropyl stuff which is poisonous to humans.
The alcohol we drink is food for certain other organisms. It would likely be turned into vinegar by acetobactor bacteria and the like and become useless as an embalming fluid.
The egyptians made beer, but are probably not the first humans to discover alcohol. It would likely have been discovered anywhere there are bees and rain in times long forgotten, probably in many locations. Watered down honey is easily fermented by roving strains of yeast, and if the acetobactor doesn't get there first, will become mead (honey wine). I imagine those first tastes weren't very good as they would have been oxidized, but obviously people got the idea that it was good stuff and refined the process as we know wine and beer making go wayyyy back. Apple cider works better as apples have a better nutrient balance for yeast, but I digress.