There is both an Original Law and an Original Buddha

The known universe is now thought to have developed from a single point of protomatter/protospirit, a chimera and kaleidiscope of beings, phenomena and elements thus developed from a single homogenous and uniform proto-entity. All Laws too are like this. They derive from the single Law of Namu Myoho renge kyo and infinite meanings derive from this single Law. In like manner, countless Buddhas derive (have been taught by) from a single Original and Eternal Buddha whose name is Shakyamuni Buddha. Thus, there is both an original Law (Namu myoho renge kyo) and an original Buddha (Shakyamuni) enlightened to this Law just as there is an original protomatter/protospirit. To say that there could not be an original cause or original teacher, goes counter to what we know of the nature, structure, and function of the universe, all phenomena, and all beings. I think you would do well to rethink your premise.