Why don’t we follow the law of Moses? (Torah/Old Testament)

^{Matthew 5:17} “Do not think that I have come to abolish the law or the prophets; I have come not to abolish but to fulfill. ¹⁸ For truly I tell you, until heaven and earth pass away, not one letter, not one stroke of a letter, will pass from the law until all is accomplished.

From what I understand, the law is unchanging, and it holds true for all ages. Why don’t we follow the laws in the Old Testament, like:

Leviticus:

• Don’t eat animals with split hooves (11:4–7).
• Don’t eat animals that don’t have fins and scales (11:9–10).
• Don’t mate two different kinds of animals (19:19).
• Don’t plant two different kinds of seed in your field (19:19).
• Don’t wear clothing made from two different types of fabric (19:19).
• Don’t trim off hair at your temples (19:27).
• Don’t trim your beard (19:27).

Also:

• Kill Burglars at Night Only
  • If a thief is killed during the night, there is no guilt. But killing them during the day is murder.
  • Exodus 22:1-3
• Don’t Boil a Baby Goat in its Mother’s Milk
  • A prohibition, possibly against cruelty or pagan practices.
  • Exodus 23:19; Exodus 34:26; Deuteronomy 14:21
• Don’t Eat Certain Types of Fat
  • Fat around internal organs (e.g., kidney fat) is for God and shouldn’t be eaten.
  • Leviticus 3:17
• Don’t Sit Where Someone on Their Period Has Sat
  • A menstruating woman is considered unclean, and anything she sits on also becomes unclean.
  • Leviticus 15:19-21
• Leave Dropped Grapes for the Poor
  • Grapes that fall during harvest should be left for the poor and foreigners.
  • Leviticus 19:9-10
• Don’t Mix Fabrics
  • Clothes made from mixed fibers (like wool and linen) are prohibited.
  • Leviticus 19:19
• Don’t Trim Your Temples or Beard
  • Avoid cutting the hair around your temples or trimming your beard edges.
  • Leviticus 19:27
• Disabled Priests Can’t Approach the Altar
  • Priests with physical impairments are barred from performing offerings.
  • Leviticus 21:16-23
• Drink Bitter Water to Test for Adultery
  • A suspected adulteress could be subjected to a trial involving drinking holy water mixed with dust.
  • Numbers 5:11-31
• Destroy Entire Cities for Idol Worship
  • Cities worshiping other gods must be entirely destroyed, including inhabitants and animals.
  • Deuteronomy 13:12-18
• Don’t Grab a Man’s Genitals in a Fight
  • A woman defending her husband by grabbing an opponent’s genitals should have her hand cut off.
  • Deuteronomy 25:11-12

If we ditch the Old Testament entirely, why should we follow any good law that the book has?

• The Ten Commandments (Exodus 20:1–17, Deuteronomy 5:6–21):
  • Worship only God (Exodus 20:3).
  • Do not worship idols (Exodus 20:4-6).
  • Do not misuse God’s name (Exodus 20:7).
  • Keep the Sabbath holy (Exodus 20:8-11).
  • Honor your parents (Exodus 20:12).
  • Do not murder (Exodus 20:13).
  • Do not commit adultery (Exodus 20:14).
  • Do not steal (Exodus 20:15).
  • Do not bear false witness (Exodus 20:16).
  • Do not covet (Exodus 20:17).
• Laws of Justice and Mercy:
  • Do not spread false reports or side with the wicked (Exodus 23:1–2).
  • Return a lost animal to your enemy (Exodus 23:4).
  • Do not take bribes (Exodus 23:8).
• Rules About Love and Compassion:
  • Love your neighbor as yourself (Leviticus 19:18).
  • Treat foreigners as your own and love them (Leviticus 19:34).
  • Help the poor by leaving part of your harvest for them (Leviticus 19:9–10).
• Honesty and Fairness:
  • Do not use dishonest weights and measures (Leviticus 19:35–36).
  • Pay workers on time (Leviticus 19:13; Deuteronomy 24:14–15).
  • Do not oppress the weak or disadvantaged (Exodus 22:22–24).
• Sexual Morality:
  • Do not commit incest, bestiality, or other sexual sins (Leviticus 18:6–23).
  • Avoid impurity and immorality, including adultery and fornication (Leviticus 20:10–21).
• Respect for Life and Property:
  • Do not murder or harm others intentionally (Exodus 21:12–14).
  • Respect others’ property (Exodus 22:1–15).
  • Return stolen goods and make restitution (Exodus 22:1-4).
• Family and Marital Conduct:
  • Honor your father and mother (Exodus 20:12).
  • Keep vows made to God or others (Numbers 30:2).
  • Protect the sanctity of marriage (Exodus 20:14; Deuteronomy 22:13–30).
• Prohibitions Against Oppression and Injustice:
  • Do not mistreat or oppress foreigners, widows, or orphans (Exodus 22:21–22).
  • Do not pervert justice or show favoritism (Deuteronomy 16:19).
• Dietary and Purity Laws Related to Holiness:
  • Do not eat blood or certain unclean animals (Leviticus 11:1–47; Leviticus 3:17).
  • Avoid unclean practices (Leviticus 19:19).
• Commands of Restitution:
  • Repay what is stolen or damaged (Exodus 22:1–15).
  • Care for borrowed or entrusted property (Exodus 22:10–13).
• Other Moral Precepts:
  • Avoid vengeance and grudges (Leviticus 19:18).
  • Act with kindness, mercy, and humility (Micah 6:8).