An interesting question, courtesy of Marginal Revolution:

Who could launch themselves higher on a trampoline? LeBron James or Simone Biles?

James has more mass & height and is stronger in an absolute sense but Biles is extremely strong for her size and is one of the world's leading experts in launching herself of off trampolines (or more properly, vault springboards).

The answer would depend a great deal on what is meant by "launch themselves higher". If the height is judged as a percentage of body weight or height, Biles wins easily. If you're talking about absolute height (as measured from the lowest point on their body at the jump's peak), James' greater mass and absolute strength works for him but Biles' ability to time her jumps to build momentum and her acrobatic skill in getting more of her body higher may put her ahead of James. If their bodies need to remain vertical at the highest point in the jump (think a basketball player's form vs. a high jumper's), perhaps that favors James, even though his legs are much longer than Biles', measuring from their centers of gravity.

From a pure physics perspective, is the trampoline just a multiplier of a person's max vertical? James' max vertical is said to be around 40 inches. Biles' max vertical is harder to determine because gymnasts jumps are measured differently, but she can get her body about 53 inches off the floor (according to this analysis). Can James get his entire body 53 inches off the floor? What's his box jump height? I imagine with various slow-motion videos, you could figure out which of them can get their center of gravity furthest off the ground...but handspringing into a layout, dunking, and bouncing on a trampoline are still not equivalent activities. The only real way to settle this is clear: let's get James and Biles together at a trampoline park and have them go at it. Netflix, YouTube, Amazon, or Twitter...make this spectacle happen!

A related question: Can Simone Biles dunk a basketball? A regulation hoop is 10 feet tall. I'm assuming she can't palm a basketball but she might still be able to do a one-handed dunk with practice. Her height plus her floor exercise max height is 110 inches, about 9'2". I don't know how high her standing reach is, but assuming a similar ratio to mine (my reach is 25% of my height), that puts her theoretical maximum jumping reach, with many caveats, at about 124 inches (10'4"). A regulation WNBA ball has a diameter of about 9 inches. Soooooo....maybe but probably not? But if not, she could surely come closer than any other person in the world who is 4'9".