Old English scinan "shed light, be radiant, be resplendent, illuminate," of persons, "be conspicuous" (class I strong verb; past tense scan, past participle scinen), from Proto-Germanic *skeinanan (source also of Old Saxon and Old High German skinan, Old Norse and Old Frisian skina, Dutch schijnen, German scheinen, Gothic skeinan "to shine, appear"), which perhaps is from a PIE root *skai- "to shine, to gleam" (source also of Old Church Slavonic sinati "to flash up, shine"). Transitive meaning "to black (boots)" is from 1610s. Related: Shined (in the shoe polish sense), otherwise shone; shining.
1520s, "brightness," from shine (v.). Meaning "polish given to a pair of boots" is from 1871. Derogatory meaning "black person" is from 1908 (perhaps from glossiness of skin or, on another guess, from frequent employment as shoeshines). Phrase to take a shine to "fancy" is American English slang from 1839, perhaps from shine up to "attempt to please as a suitor." Shiner is from late 14c. as "something that shines;" sense of "black eye" first recorded 1903, American English, in East Side immigrant dialect.