No matter what the method however, humans tend to hear what they want to hear. It's not surprising you hear that Jesus's teaching is only for you.
Different audiences, the apostles for example, may get different forms of teaching, but parables are quite communicative for the general audience. Parables communicate on several levels, every listener can get something from them, and more over time.
No, I don't think you need an Calvin Decoder Ring to get meaning from Jesus's parables:
Jesus does not say parables "are quite communicative for the general audience."
On the contrary, He tells us he is speaking in parables for the express purpose that only those with ears to hear will understand them.
Maybe you didn't read the verses by Jesus that I posted. Maybe reading them will help clarify this for you.