Does the Hadith mean that were it not for the guardian angels, the son of Adam would be afflicted by something Allah had not destined for him, and how can this be consistent with Allah being the Creator of the servants' actions, and are there matters that precede divine decree were it not for the angels' guardianship?

Everything that occurs in the universe is by Allah's decree and destiny. Nothing befalls a person except what Allah has ordained for them. No one can harm or benefit except what Allah has written. The guardian angels protect the servants by Allah's permission and decree from what Allah has not destined to befall them. However, if Allah decrees something, the angels withdraw, and what Allah has decreed comes to pass, for the angels cannot repel it.