>>212029488 (OP)A lot of Thai mythology about kingship draws on pre-Buddhist, essentially Hindu concepts that were adapted from very old Khmer models. And a lot of contemporary ideas about the monarchy were products of deliberate political fabrication and nationalist propaganda efforts just in the 20th century, mostly from periods when leaders feared unrest and were trying to manufacture ways to legitimize their regimes.
The monarch as an individual was all but irrelevant, if not completely unknown, to the masses in ancient times, and as recently as the 1920s there was widespread popular distaste for the king among many segments of society (the monarch at the time was by most standards a pretty lousy king, who nearly bankrupted Siam with frivolous pursuits and filled the court with his rough trade dockworker boy toys). The country came within inches of becoming a republic in 1932 when the absolute monarchy was finally overthrown. Instead, they set to work explicitly promoting the king as a beloved, universally known national figure.
But king worship as a central national characteristic really wasn’t a thing before the current monarch’s father’s reign.