So basically magik is whoever its holder feels it is. You do what a spell recommends as a ground-base of your belief, and alas that belief and the spell itself mold together. I get it!
This is like the feeling of time. If you ever went back in time to set off an explosion maybe that's what created you. Saying you created it, and it created you.
Meaning magic is a foundation for intelligence to learn from, and with that we intellect learn, we believe from past learning's. So with them they exist, and because they exist they happen.
Hardly anyone probably understands this, but I understand. This, this is my theory of magic.
In other words to break it down. Magik became what it is. No one knows how, it just does. Just like we exist. We exist by magik, but magik can't exist without us. Basically it lives because we do. We are all magik surrounded by a layer of bones, blood, and flesh. And because we exist we give magik a reason to exist. And because of its existence we believe in it, and in return it gives what we cast.
I don't believe magic is tied to human existence for several reasons.
1: Summoning. Summoning is the art of calling on non human beings for aid, asking them to lend their power to us. Because these beings have power, it's not all tied to us. And no, I don't believe that all the Gods are egregores.
2: Nature Magic. Whether it be herbalism, which uses magical properties in plants, various formes of folk magic/religion which use the inherent magical energy of animal bones such as Voudou, or simply communing with nature in silence, it is magic, and it's source is clearly not from us, because nature did not arise from human hands.
3: The existence of spirits before humans is clearly taught in most, if not all, religions. Whether it be Tiamat and Apsu, Ananke and Aion, Amenominakanushi, Amun, Yahweh, Pangu, Ymir, Surt, and Audumla; certain spirits have always existed before humans in every account. Since they have existed, magic exists also with them.
I do not believe magic needs us in any way, shape, or form. If no one practiced painting for a thousand years, but then someone were to come along and rediscover painting, it would still be painting. It is the same with magic. Just as the canvas, paint, and brush are all composed of the elements of this world, so too is magic, but even more so. Magic is the energy of the universe, and the manipulation of this energy is what we call any number of things, whether witchcraft, spellcraft, onmyoudo, heka, galdr, or anything else. The universe would keep on existing without us. Millions of stars shine on without humans to provide for. We are wielders of magic. I do not believe it logical to say we are its source. THat is my view. I respect your view, but I also hold it to be fundamentally flawed.