First, it is a remarkable introduction, unusual in the Old Testament. Without this introduction, Lamentations 3:1–66 would easily be thought of as a mere continuation of Lamentations 2:1–22. In Lamentations 2:1–22, the speaker is the personified woman, Zion. Now, in Lamentations 3:1–66, the speaker changes: it is a male figure who refers to himself as the man.
The term used here is not the ordinary term for a male (ish) but a rarer word (geber). This word refers to a strong man, a competent man at the peak of his physical power (see also Psalm 40:4; Psalm 34:8; Psalm 37:23–24; Psalm 94:12).1 However, this strong man has been made powerless by God. He has been the object of God’s punishment.2
1 I am the man who has seen affliction under the rod of his wrath;