Does every singular countable noun must be used with an article with it?

Question

Source
There are categories of nouns like:proper nouns, common nouns, material nouns, compound nouns, countable nouns, uncountable(nouns) or mass nouns, collective nouns, concrete nouns, abstract nouns, pronouns.

I heard a sentence in a TV series as:

You've also made clear your desire to replace me as leader of the Decepticons.

I wonder what kind of noun is the leader in this context and why it is not preceded by an article?

Another example from The Hound of the Baskervilles

I never hurt man or woman in my life that I know of.

Would the following sentences be grammatically correct?

I never hurt a man or a woman in my life that I know of.
(a could also be replaced by any).

I never hurt men or women in my life that I know of.

Answer 1

I agree that in the second example, man and woman are being used as collective nouns for humankind.

In the first example, it's not that "leader" is a separate kind of noun, but that its article is made clear by its context. You could certainly say "the leader" of the Decepticons, but by definition there is only one leader (at a time). The article isn't necessary and can be elided.

Often, we see this elision in the construction "as [noun] of [some group]" For example:

• "As captain of the cheerleading squad, Kelly is responsible for try-outs."
• "As headmaster of Hogwarts, Dumbledore knew everything that went on in the castle."
• "As C.E.O. of Apple, Steve Jobs encouraged innovation."

We see a similar non-article construction when we say someone has been "elected President of the U.S." or has "become King."

Answer 2

In the second example, I believe it's used as a collective noun meaning all men and all women. Yes, you can also use "any".