1)
What is the intent of "Mah Adam"?
1.
Rashi: What are Pras and Yishmael to You, that You made them great?
2.
Radak: This refers to Sha'ul. He was king, and his kingship ended quickly.
3.
Malbim: This refers to verse 4. Why do You recognize (esteem) man? "Adam la'Hevel Damah" - he himself is nothing!
2)
What is the meaning of "va'Teda'ehu"?
1.
Radak: Why do You consider him (recognize him and put favorable Hashgachah on him)? The same applies to "Yadata b'Tzaros Nafshi" (31:8), "Asher Yeda'o Hashem" (Devarim 34:10).
3)
Why does it say "Ben Enosh va'Techashevehu"?
1.
Malbim: Why do You esteem man? "Yamav k'Tzel Over" (4). He himself does not last, just his species endures.