Begging the question:
Do we know conclusively if the first language was spoken or written? Early man probably grunted warnings and musings - but drawing numbers and icons in the sand would have been more specific and definitive. Just pondering;0
Must have been spoken language first. Early men didn’t live in solitude like the modern painters who avoided other people by staying in their art studio.
In her Plato Prehistorian: 10,000 to 5000 B.C. Myth, Religion, Archaeology, Mary Settegast reproduces a table which shows four runic character sets; a is Upper Paleolithic (found among the cave paintings), b is Indus Valley script, c is Greek (western branch), and d is the Scandinavian runic alphabet.