put … in subjection (v.5) — a military term used of arranging soldiers in order under a commander
world (v.5) — the inhabited earth
world to come (v.5) — the Millennial Kingdom
This kingdom will not be administered by angels. An angel once was the regent of God on the first perfect earth, which angel with his associated angels administered the affairs of a pre-Adamic race. His throne was on earth. He was the anointed cherub, the guardian of the holiness of God. He struck at God’s throne, and forfeited the regency of this earth (Isaiah 14:12-14; Ezekiel 28:1-19). That angel was Lucifer. He is now Satan. The earth over which he had ruled, was rendered a desolation and a waste, and he, with his angelic cohorts, were banished. After the restoration of the earth, God placed man upon it, but man handed the scepter over to Satan, who now is the god of the world-system and whose throne is again on earth (Revelation 2:13).
But the Lord Jesus, through the blood of His cross, has regained for man the dominion over this earth, and will in the Millennial Kingdom dethrone Satan, ruling as King of Kings and Lord of Lords. The saved of the human race will be associated with Him in this reign. Thus, the angels will not administer the Millennial earth, but man in the Person of the Son of Man and those of the human race saved by His precious blood. — Hebrews in the Greek New Testament, by Kenneth S. Wuest, pages 54-55.
The force of the 4th verse of Psalm 8, the first here quoted in Hebrews 2, may be gathered from the words which immediately precede: “When I consider Thy heavens, the work of Thy fingers, the moon and the stars which Thou hast ordained — What is man, that Thou are mindful of him? and the son of man, that Thou visitest him?” In view of the magnitude of God’s creation, in contrast from the heavenly bodies, What is man? This is confirmed by the particular word which the Holy Spirit has here employed. In the Old Testament, He has used four different words, all rendered “man” in our English version. The one used here is “enosh,” which signifies “frail and fallen man.” It is the word used in Psalm 9:20! What is man, fallen man, that the great God should be mindful of him? Still less that He should crown him with “glory and honor?” — An Exposition of Hebrews, by Arthur W. Pink, page 61.
mindful (v.6) — treating with kindness
take care of him (v.6) = to look upon for the purpose of help or benefit
Therefore, “son of man” (v.6) has to refer to humanity — son of man = son of Adam. While the Psalm refers to man, the writer of Hebrews seems to use it to refer to Christ. If this is correct, it means that during His humiliation, Christ was a little inferior to angels but now is far above them.
little (v.7) — for a time, temporarily — see verse 9 where it is used the same way (Wuest — Vine says it means “degree”)
crowned (v.7) — not a royal crown, but a crown given because of exalted rank or station
glory and honor (v.7) — Adam, as the head of the race in his unfallen state in Eden
but now (v.8) — Adam, because of sin, lost his exalted state
I could see no consensus among the commentaries about which parts of verses 6-8 refer to Adam, to man in general or to Christ. I guess I think 6-8 refer to mankind — if they refer to Christ, why would we need verse 9? — but with typology of Christ. And verse 9 shows that mans’ future exaltation is in and because of Christ.