Why would God choose the long-winded route of evolution instead of using His Divinity to create man?
I don’t know, as he has not vouchsafed me an itemised decision, but I’ll speculate, if you like. Judging by what he likes about life, he rejoices in the growth of every flower from a tiny seed, and the growth of a mighty oak from an acorn. The development of a human from a single cell, carefully looked after by its parents, or a butterfly emerging from a chrysalis. They are long-winded ways of making a flower, tree, baby or butterfly, but I think God rejoices in the process as much as in the finished organism. Indeed, in the most bountiful expression of his creative joy, the insects, the finished organism last much less long than the process that took them there, before the laying of eggs and the whole thing beginning again. God rejoices in the intricacies of biological cycles, and the endless reworking of a handful of simple nutrients into the billions of different variations of organic life that have come into and out of existence like an enormously complicated kaleidoscope.
What he loves in miniature, I believe he loves in magnitude. The universe too, started as a tiny seed, the world as a simple cloud of dust, and life itself in the exquisite simplicity of a proto-cell. God does not find the process long-winded, he has loved every second, like a gardener watching his tomato-plants emerging as shoots and growing up their canes, putting out their leaves and flowers, and eventually the green, then red, tomatoes. Fifteen billion years has not been long-winded, it has been exactly right for maximum divine enjoyment.