What is the truth in this play

I would turn this around to their willingness to ignore the truth. Both Jocasta and Oedipus make convenient excuses about Laius’s murder. Tyreseus knows the truth, that Oedipus himself is the murderer that Oedipus seeks, Oedipus of course does not believe him. The people of Thebes are pretty clueless about most things. When there is a plague, for example, they carry around olive branches and want the King to save them.

I understand that the people of Thebes are pretty clueless, but it seems they pay attention to the king, in this case, which is Oedipus. So, what is their thinking towards the Truth, that Oedipus is the murderer.

Oedipus admonishes the people of Thebes that they can let a murderer go so long among them. It seems they are just as clueless about the truth.

I really Don't even understand the whole play...