Answer:
I have many feathers to help me fly. I have a body and head, but I'm not alive. It is your strength which determines how far I go. You can hold me in your hand, but I'm never thrown.
It is a path of cow juice spread across the sky but cannot be seen by the naked eye
Thousands lay up gold within this house. But no man made it. Spears past counting guard this house, but no man wards it.
Turn us on our backs and open up our stomachs you will be the wisest of men though at start a lummox.
As destructive as life, As healing as death; An institutioner of strife, Just as prone to bless. It is all that is good, Yet with an evil trend; As it was the beginning of things, It can also be the end.
I am your mother's brother's only brother in law. Who am I?