you, that
尓 centers on a second-person pronoun or a demonstrative: 'you' or 'that'. The meanings are closely related as ways of pointing to the listener or something near them.
The historical origin of 尓 is uncertain. It may be a variant or simplified form of 爾, which originally depicted a patterned weaving frame and was borrowed for its sound to mean 'you'. The modern shape does not clearly reflect that origin.
The top part looks like a pointing hand or a person, and the bottom 小 (small) can suggest directing attention to something small or specific: 'you' or 'that'.
For ジ, imagine pointing at someone and saying 'Gee, you!' — the 'Gee' sounds like ジ and fits the meaning of 'you'.