Old English helpan "to 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. Perhaps it is cognate with Lithuanian šelpiu, šelpti "to support, help."
The intransitive sense of "afford aid or assistance," is attested from early 13c. The word is recorded as a cry of distress from late 14c. The sense of "serve someone with food at table" (1680s) is translated from French servir "to help, stead, avail," and led to helping (n.) "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.
Old English help (m.), helpe (f.) "assistance, succor," from Proto-Germanic *helpo (source also of Old Norse hjalp, Swedish hjälp, Old Frisian helpe, Dutch hulp, Old High German helfa, German Hilfe), from the source of help (v.).
The use of help as euphemism for "servant" is American English, 1640s (originally in New England). Bartlett (1848) describes it as "The common name in New England for servants, and for the operatives in a cotton or woollen factory." Most early 19c. English writers travelling in America seem to have taken a turn at explaining this to the home folks.
A domestic servant of American birth, and without negro blood in his or her veins ... is not a servant, but a 'help.' 'Help wanted,' is the common heading of advertisements in the North, when servants are required. [Chas. Mackay, "Life and Liberty in America," 1859].
But help also meant "assistant, helper, supporter" in Middle English (c. 1200).