If you look closely at Buzz Lightyear from the movie Lightyear, and Bob Parr from the Incredibles, you will find that their faces look the same. Could Buzz be Bob from the past? If you think about it, Buzz is kind of like a hero. What if this inspired him to become Mr.Incredible? Buzz probably changed his name to hide his identity and have a fresh start. He could then have started a whole new life as Bob Parr/ Mr. Incredible.
Theory by Rory Mey