This is a category suggestion: get a villager to master level.
I have found that the easiest way this is to use a mason like so:

Collect 60 clay and 76 stone.
60 clay ---> 6 emeralds = Apprentice^
4 emeralds ---> 4 chiselled stone^
76 stone ---> 4 emeralds = Journeyman
Collect 60 diorite/granite/andesite^^
60 diorite/granite/andesite ---> 4 emeralds = Expert
10 emeralds ---> 10 terracotta = Master
^ For these trades, you need to click them individually to get the stone discount.
^^ The mason will have 2 journeyman trades, and there is a 5/7 chance that at least 1 of them will be a stone variant.

After not too long I got a sub 10, but this category can certainly be pushed much further with better smelting efficiency, mechanics and village proximity.

widePauseMan

Just realised that a much faster strat would be to reset for savanna villages (melons are too rare in jungles), get 28 hay bales and 12 melons (use stone tools, because killing the golem is too slow), then use those to get to a master level farmer:
(for the first 10 trades, click them individually for the discount)
28 hay bales ---> 252 wheat
100 wheat ---> 5 emeralds
5 emeralds ---> 20 pumpkin pies/apples
152 wheat ---> 8 emeralds
4 emeralds ---> 16 pumpkin pies/apples
12 melons ---> 4 emeralds
8 emeralds ---> 8 sus stew/cake
You actually only need to spend 7 emeralds to lvl them up, but it is easier just to shift click (also selling 1 emeralds worth less wheat won't work!).

I really like this run but I have one question, how did you get so many melon blocks?

In all my runs there are nowhere near enough melons.

Unfortunately that is a major run killer: you just have to get lucky with savanna villages/jungles