Historically, little is known about the exact origin or the idea behind it. However, it is known that long before 1969 (more on this in a moment) it was recognized that a central handhold between the legs makes it easier to brake and change direction. I can well imagine that adults simply watched the children playing: I also used to sit on a shovel and slide around when I was a child.
The Zipflbob uses the same principle. In 1969, Johann Uttenthaler and Siegmund Loeger put the idea into practice and developed today's Zipflbob (mini bob). In 1975, the patent rights were transferred in full to the Loeger company, which still produces and markets the bobsleigh worldwide today. With the exception of a few minor changes, the bob is still produced almost unchanged today. In the past, there have even been efforts to establish an International Zipflbob Federation (IZF). However, I don't know what the current status is and when the discipline will become Olympic. There has already been a kind of world championship in which Zipflbob races were held worldwide. The classic Zipflbob countries of Austria, Germany and Switzerland were joined by athletes from the USA, Italy and France for the first time.
