type of cypress
椹 refers to a specific type of cypress tree, a coniferous evergreen. The meaning is narrow and botanical, without broader abstract extensions.
椹 combines 木 (tree) with 甚, which likely contributes the sound. The character is used for a type of cypress, but the exact historical development of the phonetic component is uncertain.
The left side 木 is a tree, and the right side 甚 looks like a dense, layered structure. Picture a cypress tree with thick, layered foliage: 椹 is that type of cypress.
For ジン, imagine a gin bottle hidden among the cypress branches: gin -> ジン, and the tree is a cypress.