It most certainly was a massive success. But the inflation argument is still bad. There are so many variables involved that it's nearly impossible to gauge what it would have made today. And even then, making a billion dollars is still impressive as hell.
Also, fun fact. There are currently 39 movies that have made over a billion dollars, and out of them 19 are made by Disney(I'm not even counting the ones they owned later like Avatar and The Phantom Menace).