Why is this story included at all? There are many commentators who believe that this young man who fled was John Mark, the author of this gospel (Acts 12:12, 25, 13:5, 13, 15:37-39 / Colossians 4:10 / 2 Timothy 4:11 / Philemon 1:24). If so this was his way of letting us know he was there at the scene when Jesus was taken. Of course, we won’t know for sure who it was until we get to heaven.
In any event, there are no unknowns in the kingdom of God. You may not be noteworthy in the world system, or you may not be a “somebody” in the visible church realm, but if you are a Christian then you are somebody in God’s kingdom, a saint. Of course, our work is not in vain (1 Corinthians 15:58), and we will all be rewarded in heaven.
In the grand drama of the ages, there are many roles to play, and all Christians are a part of the unfolding mystery of God’s redemptive story. We may not understand why we have to go through this or that ordeal, or how this or that experience was a help to someone else. Of course, we will understand all of this and everything else when we get to heaven.
Some things may be a mystery for now, but they won’t be forever.