The people in the OT made mistakes about what God wanted and expected from them. Some of the laws that were given were in place because they were too hard-hearted to accept anything more merciful. Jesus clearly states this:
Matthew 18:30 - Jesus replied, "Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning."
The Israelites were also unwilling to heed the will of God:
Luke 13:34 "O Jerusalem, Jerusalem, you who kill the prophets and stone those sent to you, how I have longed to gather your children together, as a hen gathers her chicks under her wings, but you were not willing!"
He also clarifies a few other laws:
Matthew 5:33 - "Again, you have heard that it was said to the people long ago, 'Do not break your oath, but keep the oaths you have made to the Lord. But I tell you, do not swear at all... simply let your yes be yes and your no, no; anything beyond this comes from the evil one."
Matthew 5:38-42 - "You have heard that it was said, 'Eye for eye, and tooth for tooth.' But I tell you, Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also..."
Matthew 5:43-48 - "You have heard that it was said, 'Love your neighbor and hate your enemy. But I tell you: Love your enemies and pray for those who persecute you..."
Jesus taught us to love one another, to forgive one another (from the heart), to show compassion to the poor- in spirit and in possessions.
He taught us not to judge.
He gave approval to the humble, and condemned the arrogant and the hypocrites.
He taught us to be merciful, just as his father is merciful; for God is kind to the ungrateful and the wicked.
He taught us, 'Do unto others as you would have them do unto you." And that the greatest commands of the law are 'Love God' and 'Love your neighbor as yourself'. All the prophets and the law hang on these.
If this is so, then we begin to understand which laws were put into effect because the people were hard-hearted or unwilling to permit that love to guide them. He also argued against all those who had been wrongly condemned, insisting that the Pharisees and teachers of the law to go and learn what this means, "I desire mercy, not sacrifice."
And he did expect us to be able to make a right decision on our own. For example, when the Pharisees and teachers of the gave him and his disciples grief for healing or picking food to eat on the Sabbath, he says:
Matthew 12:11 - "If any of you has a sheep and it falls into a pit on the Sabbath, will you not lift it out?"
and
John 7:23-24 - "If a child can be circumcised on the Sabbath so that the law of Moses may not be broken, why are you angry with me for healing the whole man on the Sabbath? Stop judging by mere appearances and make a right judgment."
Sometimes Jesus said a lot by not addressing things that the jews did. For example, Jesus said that divorce was permissible on the grounds of adultery. Nowhere did he say we should stone the adulterer. Jesus is in fact silent when the jews bring him a woman caught in adultery. Only after they keep harassing him, did he say, 'let he who is without sin cast the first stone.'
The bottom line is that we learn about God from Jesus; not from the law. Whether the law was in place because the hebrews misunderstood, or were hard-hearted, or were unwilling/unable to follow anything better than what they had, Jesus came and taught us what his Father wanted from us: love and mercy.
2 John 5 - "And now, dear lady, I am not writing you a new command but one we have had from the beginning. I ask that we love one another. And this is love: that we walk in obedience to his commands. As you have heard from the beginning, his command is that you walk in love."
Tammy