者
zhě
(after a verb or adjective) one who (is) ...
(after a noun) person involved in ...; -er; -ist; (used after a number or 後|后[hou4] or 前[qian2] to refer to sth mentioned previously); (used after a term, to mark a pause before defining the term); (old) (used at the end of a command); (old) this
elder (耂) + day/sun (日) = one who does or is [something]
耂 evokes an elder, and 日 here is primarily phonetic, lending the zhě sound. Together the character became a general suffix meaning 'one who' — the elder figure hints at a person defined by their role or status.
Words with 者
舞者
wǔ zhě
dancer
者流
zhě liú
(after a personal attribute) people who have that attribute; people of that type
读者
dú zhě
reader
通讯作者
tōng xùn zuò zhě
corresponding author (of an academic paper)
逝者
shì zhě
the dead
遇难者
yù nàn zhě
victim
适者生存
shì zhě shēng cún
survival of the fittest
配送者
pèi sòng zhě
distributor
重者
zhòng zhě
more serious case
钓鱼者
diào yú zhě
angler
长者
zhǎng zhě
an elder; a senior
开拓者
kāi tuò zhě
pioneer