Gonna split my thoughts into mixing and composition.
First, the mixing. You're doubtless aware of what needs to be done; I find that louder sections (especially with the percussion) are muddy. Otherwise, it's alright, the samples you picked were excellent.
Second, and more importantly to me, the composition. I am critiquing this in light of the challenge you picked.
If there's a part of this piece that has a good bit of character to it, it's the ending, which sounds like the playful and melancholic wanderings of a street boy. You might think it was rushed, but I felt like it could be the after-intro, a means of setting the scene. I wish I heard that more. I wish I heard the emotional literacy of someone telling me the story of wonder and awe of that silent moment with the dove choosing the boy for a very solemn mission. I want to hear the quivering of the boy's voice as he struggles to come to terms with it. I want to hear the undercurrent of strength through all that weakness.
Because I didn't feel like it was there. On its own it was okay — I would still be hard-pressed to hear *your sound,* set apart from someone else's, but it's decent. In that regard, I agree with @valdamaer. When I take into account the context of the challenge, it feels like this could pass as the music of any sombre journey scene, and not specifically to do with this boy being given a vision of a solemn undertaking.
I feel heartbroken, and I had to make sure that my feelings over this piece weren't playing tricks on me, that I wasn't somehow overlooking these shiny samples or the composition.
You have doubtless taken influence from so many other composers you have heard — I want to encourage you to find the influence that makes you truly feel like their story is being told differently, and then give that your own spin. I want to encourage you to consider the environment and the emotions running through people, and I want you to give them an experience they'll never forget.