The Mosaic Law was only intended for the children of Israel of the OT.

The Mosaic Law was removed when Jesus died on the cross.

The old covenant had an important task. It revealed the coming of a new and better way which is the New Testament: "Behold, the days come, saith the Lord, that I will make a new covenant with the house of Israel, and with the house of Judah." (Jeremiah 31:31).

The Old Testament also revealed the coming Messiah. Many prophecies showed this. It prophesied Messiah's birth (Isaiah 7:14), miracles (Isaiah 35:5-6), betrayal and death (Zechariah 11:12; Psalm 22), resurrection and ascension (Psalm 2:7; 68:18; 110:1), etc.

Today we do not live according to the OT law any longer because there is not any need, but it does not negate the sound recommendations of the OT like the ten commandments. To ignore such advice would be sheer foolishness.