Old English helpan "help, support, succor; benefit, do good to; cure, amend" (transitive, class III strong verb; past tense healp, past participle holpen), from Proto-Germanic *helpanan (source also of Old Norse hjalpa, Old Frisian helpa, Middle Dutch and Dutch helpen, Old High German helfan, German helfen), a word of uncertain origin, though perhaps cognate with Lithuanian šelpiu, šelpti "to support, help."
Intransitive sense, "afford aid or assistance," is from early 13c. Recorded as a cry of distress from late 14c. Sense of "serve someone with food at table" (1680s) is translated from French servir "to help, stead, avail," and led to helping "portion of food." Help yourself as an invitation, in reference to food, etc., is from 1894. Related: Helped (c. 1300). The Middle English past participle holpen survives in biblical and U.S. dialectal use.