Several parts combine into one character.

重 originated as a compound: 人 (person) plus 東 (originally a pictograph of a tied-up sack — only later did it come to mean "east"). The composite picture is concrete labor: a person carrying a heavy bundled sack on their back. From this image of physical burden, three semantic threads grew: heavy (the weight itself) → stacked / repeated (loads pile up over time) → valued / treasured (heavy things are precious, weighty matters are important). One character carries an unusually rich semantic field rooted in the physics of weight.

Korean reading "jung." Saturates every register: 重要 (jungyo, important — the most common Korean word for "important," paralleling English's use of "weighty matters"), 重力 (jungnyeok, gravity — physics), 體重 (chejung, body weight), 尊重 (jonjung, respect / esteem), 重複 (jungbok, duplication / overlap), 貴重品 (gwijungpum, valuables). Both the "heavy" and "valuable" senses sit comfortably in modern Korean.

Mandarin presents one of the most famous tone-splits in the entire CJK system. zhòng (4th tone) carries the weight/importance senses: 重要 (zhòngyào, important), 重视 (zhòngshì, to take seriously), 体重 (tǐzhòng, body weight). chóng (2nd tone) carries the repetition senses: 重复 (chóngfù, to repeat / duplicate), 重新 (chóngxīn, again / anew), 重逢 (chóngféng, to meet again). The same character (in both traditional and simplified scripts) means radically different things by tone alone — and this is one of the most consequential 破音字 (tone-shifting) patterns Korean and Japanese learners of Mandarin must master, since their own languages do not split this way.

Japanese has two on-readings + multiple kun-readings — possibly the richest reading set of any common kanji. ジュウ (jū) for the weight/importance: 重要 (jūyō, important), 重力 (jūryoku, gravity), 体重 (taijū, body weight), 慎重 (shinchō — wait actually that uses チョウ). チョウ (chō) for repetition/preciousness: 重複 (chōfuku, duplication), 貴重 (kichō, valuable / precious), 慎重 (shinchō, prudent / careful). Three kun-readings: おもい (omoi, "heavy"), かさねる (kasaneru, "to stack / pile / layer / repeat"), え (e, an old word for layer / fold — survives in 八重桜 yaezakura, "eight-layer cherry blossom" = double-petaled cherry tree).

Memory aid: a person carrying a sack of goods — heavy, repeatedly piled on, ultimately precious. One image, three meanings.