Questions about bible verses

I've always been taught that the mosaic law and other Jewish law in the Old Testament is void because of Jesus's arrival and crucifixion, but lately I've been seeing verses that seem to contradict that.

Matthew 15:4 For God commanded, saying, Honor your father and mother: and, He that curses father or mother, let him die the death.

“Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.” ‭‭Matthew‬ ‭5:17-18‬ ‭KJV‬‬

And I often hear that Jesus fulfilled the law but heaven and earth have not passed yet