Perhaps a revised version:

The majority of the items in the first 3 books

One could say that many such non-vanilla items existed back then, but their discovery rate (by Runt, not Breeze) was lower

I'm looking very specifically at skills, non-vanilla mobs, custom crafting and non-villager people.

Eh whatever i wasnt saying youre wrong

Just trying to point out that EEG may have been saying something else

Non villager people can be vanila

Just reskin on a human

Also, stoneskin might be just be a subtype of turtle master effect

No

Stoneskin provides armor points

As such, it only protects from what armor protects from (physical damage)

Just reskin on a human

Skins don't mean anything except appearance, which is certainly not how it works

Yea

And im pretty sure you can pick a skin regardless of the race you chose

Sort of?