Jamieson, Fausset and Brown on Daniel 2:38

38. men ... beasts ... fowls--the dominion originally designed for man (Ge 1:28; 2:19, 20), forfeited by sin; temporarily delegated to Nebuchadnezzar and the world powers; but, as they abuse the trust for self, instead of for God, to be taken from them by the Son of man, who will exercise it for God, restoring in His person to man the lost inheritance (Psa 8:4-6).

Thou art ... head of gold--alluding to the riches of Babylon, hence called "the golden city" (Is 14:4; Jr 51:7; Re 18:16).