[Flyndaran]

When I was a kid, I could standing broad jump over 6 feet. So I doubt a running jump by any adult should come anywhere near that low of a distance.

And average human does not in any way correlate to Gurps 10 stat defaults.
Though I do remember some studies of athletic men standing high jumps. The norm was raising center of balance by 22 inches. Of course we can lift our long legs to clear obstacles taller than that.

Tall people will jump with their bodies over the line, and land pivoting over their feet increasing point to point distance by a few feet more than the raw center of balance to center of balance would suggest.