Singular and plural in Maoz Tzur

Question

In the first five paragraphs of Maoz Tzur, the first-person singular is used fifteen times. However, the first-person plural is used just once, in ושם תודה נזבח - and there a thanksgiving-offering we will offer. What is the reason for this discrepancy?

(I'm not considering the last stanza, which twice includes the word לנו - for us, as it was written by a different author much later.)

Answer 1

I'd heard it discussed. If I recall correctly, the suggestion was that while the song is generally describing the Jewish people as a collective entity, each person needs to give thanks in their own way.