They (the Jews) were chosen by God to bring monotheism to the world and to express it in their culture.
That choosing did not impart upon them any other special status (Jews are not better than other peoples). However, it did impart upon them special duties and responsibilities.
It's like God said "I need some volunteers for a tough mission, so I choose the Jews". They fought the mission and came back with medals.
Actually, Abraham and his physical descendents were chosen to bring to the world the seed by which all would be blessed - the Christ.
All else about the Jews is related to that purpose. Their history, culture and religion were all shadows which point to the reality found in Jesus Christ.