What does Hebrews 2:9 mean?

The writer of Hebrews quotes from the Septuagint, a Jewish translation of the Old Testament into Greek. For this reason, the phrasing of Old Testament quotes found in Hebrews may be slightly different than what's found in the same translation's text of the quoted passage. This is one example, where one can see a subtle difference in some version's quotes between Hebrews and Psalms.

In verses 6–8, the writer of Hebrews quoted Psalm 8:4–6, which described mankind as being created "a little lower than the [angels]," but yet given gracious respect and authority by God. This idea is connected, in this letter, to the idea of Messiah being fully human. His humanity is not a mark of shame, since God has already shown so much favor to mankind, as compared to the angels. In fact, Jesus' life as a man allowed Him to fully experience our struggles. This not only allows Christ to respond to us with compassion (Hebrews 2:18), it also means He actually lived a human life and can therefore serve as a perfect high priest and conqueror over sin (Hebrews 2:17).

In other words, the reason the Promised One—Jesus—was made "lower" than other spiritual beings, in the sense of becoming human, was so that He could obtain the greater victory. The entire purpose of His incarnation was in order to suffer death, but a death that would lead to eternal life for mankind. This is clearer in the original Greek, which did not rely on punctuation marks to separate phrases. Had this been written in modern English, the phrase "crowned with glory and honor because of the suffering of death" would probably have been set off from the rest of the verse by dashes or parentheses.

In the next verses, the author of Hebrews will explain more about the reasons why God would send Jesus in the way He did.