Old English ure "of us, pertaining to or belonging to us," genitive plural of the first person pronoun, from Proto-Germanic *ons (source also of Old Saxon usa, Old Frisian use, Old High German unsar, German unser, Gothic unsar "our"), from PIE *nes-, oblique case of personal pronoun in first person plural (source of Latin nos "we," noster "our"). Also compare ours.
Ourselves (late 15c.) "we or us, not others," modeled on yourselves, replaced original construction we selfe, us selfum, etc. It often is added to we for emphasis.