Have seen Interstellar twice as this work makes one think hard about the contradictory notions of how man fits into a vast reality that extends beyond knowing, something Sagan talks about at length in Contact and Nolan, in different fashion, in Interstellar.
The first part depicts environment degradation, caused by us, resulting in not only runaway global warming but also in the indirect creation of a blight that's slowing killing all plant life on earth, thus dooming man to extinction, a condition devoutly to be avoided if science, tech and courage has anything to do about it. Science and tech are vilified, the Apollo missions consigned to conspiracy and education shoved to the side as food production, in the form of corn, takes precedence over everything else, a logical choice given to just how desperate man has become in trying to survive in the latter part of the 21st century.
The second deals with science, tech and the impact of relativity and physics upon the explorers venturing out, via a wormhole, to find a viable place for man to live, which turns out, in first light, to be futile but is not due to the impact of relativity and how it enables man to unlock the secrets of black holes to save humanity from extinction through the manipulation of gravity. In seeing how this is done, one sees, for the first time, just how powerful the interpersonal impact of the twins paradox truly is, which, IMHO, rightfully places Interstellar alongside 2001 as the second greatest SF movie ever made.