What we call 'aging' is actually a microbial fermentation, esp from a historical non-sterile perspective.
There is instead other microbes that is using up the oxygen that slowly dissolve overtime in the previous fermentation step. Some are digesting/fermenting microbial biomass from the previous fermentation step.
Lactic Acid/Ethanol/Vinegar aren't the only compounds created my fermentation microbes, vitamins, solvents, numerous organic acids, esters, short chain fatty acids, digestive enzymes, etc. These compound reacts, off-gas, precipitate or are eaten by other microbes.