The shape of Latin S arises from Greek Σ by dropping just one out of your four strokes of that letter. The (angular) S-condition made up of a few strokes existed as a variant from the four-stroke letter Σ currently while in the epigraphy of Western Greek alphabets, as well https://bud-naked-flower54197.blogzet.com/s-no-further-a-mystery-46180276