偶ou3 image, pair, mate; by extension — accidental, by chance, in pair with.
It depicts a physical person on the left 亻ren2 and a statute of them on the right.
https://hanziyuan.net/#%E5%81%B6
禺CEDict defines 禺 as a monkey, but Richard Searles (Uncle Hanzi) says 禺 is the image of a hand holding a snake. https://hanziyuan.net/#%E7%A6%BA
偶尔ou3er3 paired+thou, paired+thus = sometimes, once in a while. OCCASIONAL
this occurs regularly and inevitably but rarely
经常，次数很小 ＝ 偶尔
例如：他在农村的生活很单调，偶尔的聚会还是在村里的老房子里举行，很无聊．
偶然 ou3ran2 paired+naturally = by chance, randomly
NATURALLY. BUT UNEXPECTEDLY
突然，没想到， 必然 ＝ 偶然
例如：并非偶然 ＝ not by chance