I was puzzled...till the parable was explained

Parables are just stories to drive home an idea.

I was puzzled by this parable for a long time:

There was a landowner who planted a vineyard and put a wall around it and dug a wine press in it, an built a tower and rented it out to vine-growers and went on a journey. And when the harvest time approached, he sent hus slaves to the vine-growers to receive his produce. And the vine-growers took his slaves and beat one, and killed another, and stoned a third. Again he sent another group of slaves larger than the first; and they did the same thing to them. But afterward he sent his son to them, saying, 'They will respect my son.' But when the vine-growers saw the son, they said among themselves, "This is the heir, come, let us kill him, and seize his inheritance." And they took him and cast him out of the vineyard, and killed him. Therefore when the owner of the vineyard comes, what will he do to those vine-growers?

They said "He will bring those wretches to a wretched end, and will rent out the vineyard to other vine-growers who will pay him the proceeds at the proper seasons."

Jesus said to them, "Did you never read in the Scriptures, THE STONE WHICH THE BUILDERS REJECTED, THIS BECAME THE CHIEF CORNER STONE; THIS CAME ABOUT FROM THE LORD AND ITS MARVELOUS IN OUR EYE?" (Matt 21)
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The parable explained: The protagonists in this parable refer to:
Landowner refers to God
Vineyard refers to Israel
1st tenant looking after the vineyard refers to pharisees and sadducees
Sending 1st group of servants refers to the early prophets
Sending 2nd group of servants refers to the latter prophets
New tenant looking after the vineyard refers to the apostles
Sending his son refers to Jesus
1st lease refers to the old covenant
New lease refers to the new covenant

This parable refers to how patient God is with His people, Israel.