I tend to think a lot of ideas are your subconscious/your gut communicating its desires with you. Because everything we do is something that we believe will benefit our happiness and survival, and they always say to trust your gut- your innermost, naked self. But who knows, maybe it is some deity or higher being giving us instructions on how to achieve inner peace. The more you know about the world and the universe, the more you don't know, y'know?
So my real answer is.. I don't know. I don't think anybody does, all we have are theories and best guesses. Nobody truly knows where they come from, if they are our own, or what they are. Regardless, they are a beautiful gift, and I consider myself lucky to be conscious and creative.
BoiledMilkz
https://www.youtube.com/watch?v=SOLSIHb6zhk
JensVide
Well the video is undoubtedly creative. I have many little notebooks like the one in the video full of little notes and drawings. The video is humorous and maybe a bit cynical but there is some deeper truth to the part about the muse.