1)
Why does it say "Peh Lahem v'Lo Yedaberun"?
1.
Radak (5-6): They make them in human form, but they cannot put Ru'ach in them to enable them to speak, see or hear. It lists the five senses, for which they have the form [of the limbs that sense], but they do not sense. 1
2.
Malbim: Their form is lowly. The form of man is speech, and the form of living beings is sensation and motion. They lack these, like the verses describe.
1
I do not know why speech is called a sense, but also Pesikta Zutresa (va'Eschanan 5b) includes speech and walking among the five, and omits taste and smell. Midrash ha'Gadol (Vayikra 2:1) holds oppositely. (PF)
