When we introduce something in general, what pronoun to use? "one" or "she, he, it"?

Question

When we introduce something in general, what pronoun do we use?

Is it more correct to use the indefinite pronoun "one" first and then use the definite pronoun "he", like Example 1?

Do you think both Example 1 and Example 2 are correct?

Example 1

A: What is a soldier?

B: A soldier is a man who know how to use a firearm and protects his country. One usually learns the basics of weapons in the bootcamp. After the bootcamp, he is dispatched to a unit.

Example 2

A: What is a soldier?

B: A soldier is a man who know how to use a firearm and protects his country. He usually learns the basics of weapons in the bootcamp. After the bootcamp, he is dispatched to a unit.

Answer 1

In this instance, "one" is incorrect. Only Example 2 is correct.

When we introduce something in general, what pronoun do we use?

The function of "he" is not to "introduce something in general", but to refer back to something that has already been introduced. The word "one" is never used to refer back to something that has already been introduced. In both examples you've given, the concept is introduced with the phrase "a soldier".

However, "one" can be used to introduce a very general subject, for example:

One should always be careful.

In this case, "one" means "anyone" or "everyone".

A final point I would make is that "he" is correct in the second sentence because the soldier has already been established to be a man in the first sentence. In case the gender is not certain, the word "they" can be used:

A soldier is someone who knows how to use a firearm and protects their country. They usually learn the basics of weapons in boot camp. After boot camp, they are dispatched to a unit.

Note that it should be "knows" rather than "know", and "in boot camp", not "in the boot camp", as I've highlighted.

Answer 2

Third person pronouns in American English have traditionally had the property of markedness, where the male form is unmarked and the female form is marked.

For examples, the noun "lion" and "actor" are unmarked while "lioness" and "actress" are marked.

"Look at the lions over there!" could be the speaker referring to a group of only males lions, a group of only female lions, or a group of mixed male and female lions. "Look at the lionesses over there!" must mean that the group only has female lions. The Screen Actors Guild is an active group in Hollywood. Both male actors and female actors can be members. But, The Screen Actresses Guild would only make sense if the members were exclusively female.

This is because of(lion / lioness) and (actor / actress) having an (unmarked / marked) relationship.

Traditionally, in US English (he / him / his) and (she / her / her) also have had an (unmarked / marked) relationship. The male pronouns were never assumed to exclusively have male antecedents, while female pronouns are required to have female antecedents. This was not because of sexism. This use of markedness simply removed the need to always say "he or she", "her or him", and "his or her" when the gender of the antecedent is unknown.

In formal writing, I am confident in continuing to use markedness. In current daily conversation, I'm a little unsure if using markedness is still considered ok. Languages change over time.