Woah, this is pretty neat for many different reasons. First of all, with such a limited instrument choice, you really managed to create an amazing composition without many instrument layering. Secondly, the melody does feel like something that would fit climbing, with different parts to the mood such as gloom, desperation, uncertainty, but also somewhat perseverance-y. The wind effect was really cool too! At 3:48 it gets crazy though, as if you're finally almost there or just getting closer to the climax. And at 5:12 everything changes! The song gets happy, uplifting, and feels like it let's go of all the tension the listener builds up with a good ending. All this stuff together makes it feel like you're telling an awesome story with all those mood and energy changes. And a last thing, the composition style really reminds me of classical music, which is pretty cool considering the instruments you used.

I'd love to say much more but in general I can just say amazing work, and keep it up!!