singular or plural pronouc for unidentified third person

[determine]

"So when a person says he or she is humbled, are they saying that he or she has been made unassertive, unpretentious, or insignificant?"

from Meyam Webster World for the Wise.

Can we say: is he or she saying vs. are they saying...

What is the grammer rule?
Thank you very much
d

[abaka]

Traditionally, "he".

Today, "he or she", or informally "they".

Aspirations to unreal equality have damaged the construction so much that it may be a good idea to avoid it at all costs for now, at least until "they" becomes universally accepted.

So when a person says, "I am humbled", does that mean made unassertive, unpretentious, or insignificant?"

[determine]

Thank you very much.