As for Chamberlain, maybe he didn't get any of those marks in high school, but maybe he did. Maybe he jumped 6'6" in practice.
Who knows? But he did jump almost 6'7" in college. And while he didn't put the shot over 50' in college, the college and high school shot were not the same weight back then, so maybe he did get 53' in high school. Your college shot is going to be worse than high school for a while at least because it's heavier. I don't think anyone would doubt that as he got stronger during his career he wasn't capable of putting the shot over 60'. As for the speed, well, he may have been among the fastest on the basketball court for many years in the NBA.
Here is footage of Wilt winning the Drake Relays in 1957 with 6'6" 1/4 in the high jump. You can obviously add a bunch of height to that if he were doing the Fosbury Flop a decade plus early.
There's a face off between Wilt and Ali on Howard Cosell's show where their armspan is measured. Wilt's is 92". His hands are not measured but they absolutely dwarf Ali's.
At 10:05 of this video, there is a claim that Wilt ran a 4.6 hand-timed 40y dash in 1966, a 13' maximum reach in a jump in 1960, and a bench press of 500 lbs (465 even at age 59). Arnold Schwarzenegger states that Wilt would do triceps extensions of 160 lbs when the best weightlifters around could do only about 110-120 lbs.