Which important concept of Judaism has spread to Western civilization?

Answer 1

You have asked a wide-ranging question with many hundreds of details in its answer. I'll provide a few examples.
The long, rich history of Judaism gives the western world much of its shape today. Many of the laws, traditions, culture and values are directly attributable to Judaism.
1) The Jews' monotheistic religious tradition shaped the Western beliefs about God.
2) The 7-day week, including a day of rest for everyone.
3) The concept of morality was also the work of the Hebrews, including the dignity and value of a person. Women's rights also were carefully maintained in this ancient culture. Israelite women could own property, could initiate court cases, could have their own servants, and could own fields and businesses; and the Torah specifies marital rights for women (Exodus 21:10). Today's laws giving women equal rights under the law are a by-product of Judaism.
4) Under Israelite law, everyone had recourse to the courts. A child, widow, wife, etc., could initiate legal action against any citizen to redress perpetrated harm. Compare this to those societies in which only mature, land-owning males had any legal status.
5) What is customary to be eaten in Western society is a reflection of much of the Judaic dietary law. With the exception of the pig, Western society does not eat species not contained in kosher law. Owls, mice, insects, rats, snakes, cats and dogs are not eaten by most Westerners and it is a direct result of Jewish culture.
6) Parents are responsible for teaching children. Illiteracy among Israelites, in every generation, was rare. Universal education in the Western world is taken for granted today, yet this is a recent development. In Judaism, however, it goes back 3300 years. Judaism has always maintained that education is the highest goal of man in his pursuit of Godliness. This tradition has now been passed on to Western culture.
7) Infants are to be protected and cared for, whether or not they turned out to be the gender you were hoping for. Compare this to societies in which unhealthy babies, or females, were killed.
8) Cruelty to animals is not acceptable.
9) Government is accountable to a higher authority. In other ancient societies, the monarch was all-powerful. Among the Israelites, however, the king was under the constant scrutiny of the Divinely-informed prophets, who didn't hesitate to castigate him publicly for any misstep in the sight of God. And, other than for the crime of rebellion, the king couldn't punish any citizen by his own decision. He was obligated by the Torah-procedures like everyone else.
10) A robber repays double to his victim, or works it off. Cutting off the hands of a robber is a punishable crime. Debtors are not imprisoned or harmed. They are made to sell property and/or work to repay what they owe. Compare this to the Roman practice by which anyone could accuse a man of owing them money and the debtor could be killed.
Western jurisprudence in general is based in part upon Judaic Torah observance. A quick look at the Ten Commandments (Exodus 20) and the laws that follow (Exodus ch.21-23) gives a very good summary of most modern law.
11) It is the responsibility of the community to support the widow, the orphan, the poor, and the stranger passing through.
It is important to note that every one of the above was instituted among the Hebrews (a.k.a. the Israelites) thousands of years earlier than in other nations. Here's just one example: Aristotle, who was among the greatest of the Greeks, and Seneca, the famous Roman, both write that killing one's young babies is perfectly acceptable.