The teacher gave an in-depth analysis of this question.
Tips
usage
作 and 做 both mean 'to do' but 作 is more literary/abstract (写作, 创作, 合作) while 做 is colloquial/concrete (cooking, building, physical tasks).
register
作 has a second reading 作 - bound form meaning worker/workshop (作坊) and a modern slang verb 'to court trouble / be melodramatic' as in 作死. Default to 作 - the zuō reading is rare outside fixed compounds and internet slang.
Left person radical - side-form of 人. The indexing radical (Kangxi #9). Doing, making, working are all things people perform, so the human focus is literal. Same radical heads 你, 他, 们, 住, 修 - the bulk of person-related vocab and human-action verbs.
Right component supplies the sound (zhà → zuò, a regular old-Chinese palatal-to-affricate drift). 乍 itself originally pictured a knife cutting a sleeve, the act of starting work on a garment, which is sometimes read as a faint semantic echo of 'beginning a task'. Same phonetic in 昨 (yesterday), 怎 (how), 炸 (explode), 窄 (narrow).
