"In the Likeness of Sinful Flesh", "In the Likeness of Men" (Rom.8:3, Phil.2:7) - Barnes and Zodhiates

ἐν ὁμοιώματι σαρκὸς ἁμαρτίας (Rom 8:3 BYZ)
in the likeness of sinful flesh (Rom 8:3 NAS)
Albert Barnes:
"That is, he so far resembled sinful flesh that he partook of flesh, or the nature of man, but without any of its sinful propensities or desires. It was not human nature; not, as the Docetae taught, human nature in appearance only; but it was human nature without any of its corruptions."

Zodhiates, Word Study:
homoíōma; gen. homoiṓmatos, neut. noun from homoióō (G3666), to make like. Likeness, shape, similitude, resemblance. It is important to realize that the resemblance signified by homoíōma in no way implies that one of the objects in question has been derived from the other. In the same way two men may resemble one another even though they are in no way related to one another....
In Rom 8:3, "For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness [homoiṓmati] of sinful flesh, and for sin, condemned sin in the flesh." Paul indicates not that the body of Christ was merely human, but that in spite of His having a real body and a truly human nature, yet these were only similar to ours, without sin or the propensity to sin.
ἀλλ᾽ ἑαυτὸν ἐκένωσεν, μορφὴν δούλου λαβών, ἐν ὁμοιώματι ἀνθρώπων γενόμενος (Phi 2:7 BYZ)
but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men. (Phi 2:7 NAS)
Zodhiates, Word Study:
In Phil. 2:6-8, three synonymous words occur:
(A) The first word is morphḗ, form or inward identifiable existence. Christ's identification as God in heaven is clear, "Who being in the form of God thought it not robbery to be equal with God [He was not made equal to God but that He always was of the same essence as God and of the same rank {cf. Joh 1:18}]" (Phil. 2:6). No person could be in the form of God and not be God. In Phil. 2:7, the Gr. text simply says, "But He emptied Himself." ...
In His incarnation, however, He voluntarily took on the form of a man and His humanity was fully recognized by men on earth. While He lived on earth as the God-Man, He was simultaneously the Son of God in heaven. In other words, He did not empty Himself of His divine perfections nor of the essence of His being, but He emptied Himself into a life of humiliation that was itself emptied into death.
....Jesus Christ did not have His life taken from Him. He died because He chose to die (Joh 10:17-18).

This is the reason why in Phil. 2:7 for the statement that Jesus "was made in the likeness of men [en homoiṓmati anthrṓpōn]"; and in verse eight that He was "found in fashion as a man [hōs ánthrōpos]." In shape (schḗma), He was exactly as man. In this instance the words homoíōma, likeness, and schḗma, shape, are parallel. In His essence (morphḗ) He was God, but took upon Himself, in addition to His deity, the likeness of men (with a true human nature in a real body), yet without sin (Heb 4:15). For this reason we are told that he was made en homoiṓmati anthrṓpōn, "in the likeness of men," not merely that He became man.

(B) The second word that is used in Phil. 2:7 is homoíōma, "But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness [homoíōma] of men." Paul declares here that Jesus Christ, whose essential preincarnate form was spirit (pneúma), emptied Himself and took upon Himself the form of man. But His was, as Rom 8:3 says, not the flesh of sin, but sinless flesh....

(C) The third word that occurs in the Philippian passage (Phil. 2:8) is schḗma, form, fashion. It refers here to the physical form that Jesus took. Schḗma is more closely related to homoíōma, likeness, than to morphḗ, form or substance, essence. "And being found in fashion [schḗmati, sing. dat. of schḗma] as a man, he humbled himself, and became obedient unto death, even the death of the cross." The Lord Jesus did not deliver His divine nature to man to kill; His spirit could not be killed. His enemies, failing to recognize His deity, found "a man." This one they killed, not knowing that He was indeed the God-Man. Even so, the Apostle Paul tells us that the only reason they could kill Him was that "He humbled Himself, and became obedient unto [until] death, even the death of the cross."

The death of Christ was an act of obedience. The death of Adam was the result of disobedience. In His death, Christ was essentially sinless. He was the sinless Lamb of God who took away all the sins of the world. He was made sin (2Cor.5:21); but, not sinner; for He is the Righteous One, the Holy God manifest in flesh. He offered Himself for our sins. Therefore, death could not hold Him (Acts 2:24). And, He is able even to subdue all things to Himself (Phil.3:21).