The purpose is "to promote the progress of science and the useful arts", the method is "by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries".

In this case, the Work was created by the monkey. Yes, the camera owner helped, but he doesn't meet the established criteria of the Author in existing copyright law. Nor does the monkey (works of nature are not copyrightable).

You can disagree with the law as it exists (I think terms should be drastically shorter, and in no case should copyright be extended retroactively), but it takes an act of Congress or the courts to change it.