God made humans that way in making them in his image. God does as he wishes--it may be his most fundamental quality. No being is freer of necessity than God, for who or what is there that could impose necessity upon him? He could have created the universe, or he could have not. He could have made beings like us in his image, or he could have not. But God did make us in this image of freedom, excepting of course, that he could not make himself, so the image is not as powerful, nor as free, nor as able as the original.
Nonetheless, that created in the image has to be free in a way analogous to God or it would not be in his image. If God determines our desires or decrees our choices we are no more free than a robot, and nor more in his image than a robot can be in ours. If our choice is circumscribed by desire, the result is not freedom but mere instinct. The Bible generally (there are specific exceptions) shows humans in a light in which the kind of choice described thus far would have to be presupposed in order for the accounts to make sense.
Fallen humanity does has the power of choice--the freedom to do as they wish. Their wishes, however, can never rise to nor align with the choice of God. Apart from the Spirit of God communicating the word of God into the soul of a man and thereby enabling faith, that man is not free to do as God wills or, indeed, to know what that is. With the action of God's Spirit bringing to bear God's word on the human heart and giving faith the opportunity to arise, something other than the general depravity of mankind is possible.