The individual tales follow a recognizable shape. Nasruddin is asked a question, given a task, or put in a position where sensible behavior is expected, and he answers with something that looks like simple stupidity until the logic underneath it turns out to be sound, or turns the situation's own assumptions back on the person who set it up. In one widely told version he is seen searching under a streetlamp for a key he dropped inside his house, because, he explains, the light is better there. Read as comedy the joke is on him. Read as a teaching story the joke is on anyone who has ever looked for an answer where it is easiest to look rather than where it actually is.
This double reading is why Sufi teachers in particular adopted the corpus as a vehicle for instruction rather than treating it purely as folk humor. A trickster's foolishness can carry a spiritual point that a sermon cannot, because the listener has to do the work of finding the reversal rather than being told it directly, and a lesson arrived at that way tends to stick. The same story can be told to a child as a joke and to a student as a problem to sit with without either telling being wrong.
The figure's usefulness for teaching, more than any historical record, is why he survived and multiplied across so many languages.