Pls note these might not be acurrate, but they probuly are...not :(
the GREAT list of minecraft classes (originaly made for 1.12)

Info:
[Cname]$[Letter/Number] = what is used to attach class files
Not all Cfiles have descriptions, they go with the catagory

font/text/etc:
a = what seems to be the main font text
aak = what seems to "name" the letters
afp = something that connects to "com/google/common/collect/Lists" which isnt a directory
aua = something with caps
aut = i think it loads usernames
bae = helps make bae MC text :3

Entity:
bc = villager & trading

Messages:
kk = the java.lang.IllegalArgumentException errors we all hate
nq = tells you that you messed up custom advancements

Servers:
l = advancements for servers
bks = "multiplayer_StopSleeping" doesnt let you sleep unless everyone is?
nn = connection
nr = seems to load functions on servers

world:
m = takes you to spawn when you die, also sets spawn with bed, and something with "entity kills player"
mg = gets a uuid from the site
om = gamerules, functions, data, structures,pretty much level.dat management


miscellaneous:
age = something with a snowman emoji
ai = i think it lets google(minecraft) have better prepormance in web mode
bb = something online or with lang file
md = mojang, keeping empty classes in the files sence 2009