I am having problems with when to understand 大抵 as:

a)　事柄のあらまし。だいたいのようす。また、全体のうちの大部分。おおよそ。おおかた。(https://dictionary.goo.ne.jp/word/大抵/#jn-133918) (or as defined in Apple's dictionary) 全体の中の大部分のもの。ほとんどのもの。大体。

b) ほとんどすべてに及ぶさま。たいがい。https://kotobank.jp/word/大抵-557812

While I am aware of the difference between noun and adverb I saw the sentence:

1. 「大抵は魔法使いの エキスパートで―…」

translated as: "In general they are experts in using magic"

However I initially understood it as: "Most of them are experts in using magic" (especially sticking to the definition referred to in the Mac-dictionary)

I first came across this word in:

2. 「大丈夫だって。大抵の奴はわからんよ。」

In that case the meaning was pretty clear to me and according to its meaning here I thought in 「大抵は…」　its meaning is the same as in 2).

Context: (Season 1 Episode 2 of このすば) The "race" of Crimson-Demons is explained and general characteristics of them are listed and the this sentence is some kind of "conclusion" to it.