silk fabrics, surname
繒 centers on silk fabrics, referring to woven silk textiles. The surname sense is a separate application of the same character.
繒 combines 糸 (silk thread) with 曾, which likely contributes the sound. The character originally referred to silk fabrics.
The left side 糸 is thread, and the right side 曾 looks like a loom or layered weaving. Picture silk threads being woven into fine fabrics.
For ショウ, imagine a show of silk fabrics: show -> ショウ, and the silk threads 糸 are displayed.