Well, this is pretty obvious. The Great Deku Tree says this about the Koroks:
What do you call yourself? Link? Well then Link... These are the Koroks---the spirits of the forest. Once upon a time, long ago, the Koroks took on human forms, but when they came to live on the sea, they took on these shapes.
If you need confirmation of this because you don't trust me or whatever, watch
this video.
And if you need further evidence (which you shouldn't but whatever), read this.
I am Fado of the Kokiri Tribe. I know I appear to you as a child, but the eyes can oft deceive. I am a most esteemed sage.
This confirms that he is a Kokiri.
You wish to restore the power to your blade, don't you? In that case, look for the one who has the same instrument that I hold, and teach him the song you just played. Once you do, I'm certain the holder of the instrument will feel the blood of the sages awaken within his veins.
Again, if you don't trust me, watch
this video and see the same thing.
Okay so to sum it up, the Great Deku Tree said that the Koroks once took on human forms (which obviously means the Kokiri) and Fado, the once Sage of Wind, said that once Link plays the song he just learned (Wind God's Aria) that the new Sage of Wind (Makar, of the Koroks) will feel the blood of the sages awaken within his veins. If that doesn't make it so obvious an idiot could understand, I don't know what will.