Jesus' parables are stories which use earthly concepts as analogies for the kingdom of heaven. These concepts are mostly agricultural; not only would they have been familiar to his first-century audience, but they make sense all over the world. Every culture has to grow food.
The context of this parable is important. Jesus' authority has just been questioned by the Jewish religious leaders, and he has refused to answer on account of their hypocrisy. Immediately after the parable, Luke tells us that the religious leaders wanted to "lay hands" on Jesus because they perceived that he had told the parable against them. This seems to be an example of their pride but also their knowledge of their own sin: the parable has a broad application, but the religious leaders assume that it is directed only towards them. This parable therefore sits in a section of Luke that illustrates Jesus' opposition to the contemporary religious establishment, and it explains why his message is so different to the teachings of the religious leaders.
The story Jesus tells is fairly straightforward: wicked tenants escalate their evil as the landlord escalates his attempts to restore the proper relationship. After the tenants kill his son the landlord will come and destroy them and give the vineyard to others. Jesus grounds this ending by quoting from Psalm 118:22, linking the parable to prophecies about the messiah and implicitly declaring himself the Messiah. His audience is presented with two options: they fulfil the terms of their lease and obey God, or be ejected from the vineyard and destroyed. Salvation is not a matter of following rules and regulations, but a binary choice: accept his authority or reject his son.
The religious leaders do not recognise Jesus' authority even though it is evident in every word he says and even the manner in which he performs miracles. This is their failing. Obedience and the struggle to be a good person is nothing if you do not submit to the Lord's authority - which is coterminous with his son's. Unlike the scene in Luke where Jesus tells this parable, we are living after the crucifixion and resurrection, so Jesus' authority has even greater significance: we are not cleansed of our sins unless Jesus was perfect, and we are not free from death unless Jesus conquered it. Obedience and salvation on one hand, rebellion and death on the other: easy choice.