You will find in the Gospels that Jesus quoted the Old Testament many times.
"All Scripture is given by inspiration of God..."
Not just the NT.
Those who want to throw out silly questions like the blended fiber clothing line reveal their lack of good Biblical understanding.
Do we throw out the 10 Commandments?
The wisdom of Poverbs?
The comfort of
Psalm 23?
The handwriting of ordinances, the ceremonial observances, the animal scarifices, all these were nailed to the Cross.
But things in the Old Testament that reflect God's unchanging moral nature are still binding today.