I read Psalm 8 for my personal Bible study this morning and I don't understand who David is referring to when he says "son of man." I know that this phrase later on described Jesus (lower than the angels). But who is David referring to? The Messiah or... -- E.J.
The mark of Hebrew poetry is not word rhyme, as in so much western poetry, but thought rhyme. That is, something is stated and then said another way. Man and Son of Man are parallel, and mean the same thing. In Hebrew, "son of" often means "a member of group x." A "son of the prophets" means that the man is a prophet. (It says nothing about his father!) So Psalm 8 is referring to humankind.
Yet there is a deeper meaning here, and Jesus often used the term and applied it to himself. "Son of man" appears in Ezekiel, referring to the prophet himself, and in Daniel, referring to the Messiah. Son of man emphasizes that Jesus is truly human. Thus Jesus emphasized his solidarity with us, his fellow humans.
In the early church, this was a hard thing for many people to believe. They preferred to think of him as something more like a phantasm than a real person, or God in human flesh.
Finally, in Hebrews 2:8, the passage if Psalm 8 is applied to Christ. This is a legitimate application because he is our representative, the archetypal man. He lives up to God's original hopes for his human creation. But then that is another discussion.