Aside from your (occasional) penchant to try and treat a metaphor as a subject for scientific inquiry, I think your "improvisational jazz" suggestion is useful. It certainly provides a metaphor of life and creation as experienced in any given moment. When my sense of humor kicks in, I sometimes imagine an encounter with God when all history has played out. He greets us and agrees to take a few questions. When we mention the various music metaphors, God exclaims: "Music! What music? Me, I'm a gardener!"
We've arrived at the final paragraph of the Sermon on the Mount. It reads: "Everyone then who hears these words of mine and acts on them will be like a wise man who built his house on rock. The rain fell, the floods came, and the winds blew and beat on the that house, but it did not fall. And everyone who hears these words of mine and does not act on them will be like a foolish man who built his house on sand. The rain fell, and the floods came, and the winds blew and beat against that house, and it fell--and great was the fall." Now when Jesus had finished saying these things, the crowds were astounded at his teaching, for he taught them as one having authority, and not as their scribes. (Matthew 7:24-28, NRSV)
A childhood chorus first imprinted the story on my mind. Repeating lines about the falling rain and the rising flood, coupled with appropriate body movements, led to a conclusion in which the wise man's house stood but the foolish man's house "came tumbling down." We were easily entertained in that era!
In the context of The Sermon on the Mount, Jesus' words constitute both warning and invitation. Listening to, digesting, attempting to structure life in accordance with his words matters. Many Christians over the centuries have taken the injunction to imply that the Sermon on the Mount is the literary core of Christianity. Those who do so, tend to read the remainder of the gospels and the rest of the New Testament in light of The Sermon on the Mount. In short, the sermon becomes a "canon within the canon."
It's worth recalling how counter-intuitive the sermon feels to most of us. In an era when many, perhaps most, believe safety is found in violence, even pre-emptive violence, the sermon speaks of loving an enemy, of doing unto others as we would have do unto us, and the like. At almost any point in the sermon, we find ourselves confronted by an alternative vision of personal and community life. Frankly, I find it requires a bit of a leap of faith to attempt to embrace and practice the sermon's core teachings.
With regard to the parable itself, it assumes a setting in which heavy rain and floods are rare enough to enourage short-cuts or complacency. The parable's images are heavy-handed, designed to contrast the stark difference between foolishness and wisdom. As I have noted before, it seems to me he draws upon the tradition of the two ways, in this case clothing it in talk of two ways of selecting a home site.
The Sermon on the Mount closes with a summary statement of the crowd's reaction to the entire speech. Christian scholars have invested a great deal of ink and paper in the attempt to understand the text's contrast between the scribes and Jesus approach to teaching. More often than not, they suggest the "scribes" tended to teach on the basis of an inherited tradition, relying on the authority of those cited. The same scholars suggest that Jesus, in contrast, spoke as one with a word from God, whether in a sense similar to that of earlier prophets or as the Messiah. Frankly, I doubt we can discern the gospel writer's intent at this historical distance, other than to say he believed Jesus taught with a authority his listeners found novel.