fathom
仞 centers on a unit of depth or measurement, specifically a fathom, which is the length of outstretched arms used to measure water depth or height.
仞 combines 亻 (person) with 刃 (blade), likely representing a person measuring with outstretched arms, the original fathom. The exact historical development is uncertain.
A person 亻 using a blade 刃 to measure a fathom's length: imagine a person holding a sword at arm's length to gauge depth.
For ジン, picture a person measuring a fathom of gin (the drink) with a blade: gin -> ジン, and the person stretches to measure the liquid depth.
great height
to fail one step short of great success; to fall at the last hurdle
ren (ancient Chinese measure of height, depth, etc.; between 1-3 meters)
precipitous cliff of great height, metaphor for absolute nature of Buddhist truth