I don't have my Hebrew lexicon handy at the moment, so I'm not sure how often "chaciyd" versus "qadowsh" is used. However the term qadowsh (holy one) is used in a plural sense:
Psa 34:9 O fear the LORD, ye his saints: [sic: qadowsh] for [there is] no want to them that fear him.
What the Lutherans called them is immaterial. I'm not Lutheran.
The LXX uses holy angels so obviously it is not about people. Job 2:1 in Hebrew calls angels sons of God. This is a pattern throughout the Bible, conveniently ignored when it suits a particular reader.
Son of Man (in Hebrew ben Adam) simply means son of Adam (like the son of Abraham), denoting a lineage and nothing holy. It "becomes" holy in the NT (butthen the Nt was written for the Greeks who klnew nothing of Judaisn, nor did they speak Hebrew).
The same goes for the meshiyah (messiah), whose meaning in Hebrew is nothing like the NT "Christos." The anointed was any Jewish king. All Jewish kings were believed anointed and appointed by God.
The same goes for the "World to come" phrase, or the "Kingdom of heaven." This phraseology changed meaning the way English word "gay" attained different meaning over time. But they were used with specific goal (and meaning) in mind.
Which is okay, as long as we remember that this is something we could call man-made tradition, choose and preference.