While the earth and its creatures may serve other purposes of which we are unaware of, Man is given permission for the fulfillment of his human calling, to make use of (only) those creatures he may need. If Man does this truly as אדם, a representative of God, the world will gladly allow this. When used in this way Man is not enslaving the creatures but rather elevating them into the sphere of serving God out of free will (a sphere that they alone, as animals, do not live in GS).
Originally (the first 1526 years) Man is not allowed to kill living creatures.
God gives Man more complete control over the raw materials of the earth to use all of it and puts his stamp on it, molding and making use of it as he sees fit.
Beraishis 1 27-28, Pages 31-32
