"unable to act for oneself," c. 1200, from help (n.) + -less. Related: Helplessly; helplessness. In Middle English and later sometimes "unable to give help, affording no help" (late 14c.), but this never was common.
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).
word-forming element meaning "lacking, cannot be, does not," from Old English -leas, from leas "free (from), devoid (of), false, feigned," from Proto-Germanic *lausaz (cognates: Dutch -loos, German -los "-less," Old Norse lauss "loose, free, vacant, dissolute," Middle Dutch los, German los "loose, free," Gothic laus "empty, vain"), from PIE root *leu- "to loosen, divide, cut apart." Related to loose and lease.
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Harper, D. (n.d.). Etymology of helpless. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/helpless