The final act of Interstellar was a bit of mess, packed with feel-good mystical pseudoscience that was out of place in a sometimes glorious space opera. It turns out that ending was all director Christopher Nolan's idea and that Jonathan Nolan's original script called for a more straightforward—and darker—ending.
The Nerdist reported on a media event where Jonathan Nolan (who wrote the original Interstellar script and worked with his brother Christopher Nolan on the final version) and Interstellar science advisor and producer Kip Thorne were promoting the home media release of the film. When someone brought up the movie's ending, Jonathan Nolan revealed that his original script gave Cooper a very different ending.
Here's how the Nerdist describes the change:
Jonathan Nolan's much more straight-forward ending "had the Einstien-Rosen bridge [colloquially, a wormhole] collapse when Cooper tries to send the data back."
So no tesseract (that was Christopher's idea), no time manipulation, and no return home. Nolan didn't elaborate on this point, but we might speculate that the original end to the movie was as dark and unforgiving as space.
So it sounds like that would have been the end for Cooper. He would have sent the data without knowing if it had reached Earth or if the people back home would be able to use it. There would have been no reunion with Murphy and no raising babies with Dr. Brand. Cooper would try to be the hero, but he wouldn't get to see if he succeeded — none of this "love transcends dimensions of time and space" mumbo-jumbo.
Now that's a version of Interstellar we would have really liked to see.