et al,
I like the idea of the "wheel" and "language." But I'm not so sure that it is correct.
(OPINION)
The importance of very early inventions, are that the were essential to the survival of the species. Before the wheel, and probably before language, it was something simple, like the knife or spear that allowed man to survive. Without the knife
(sharp edge instrument), clothing from animals would have been difficult.
There is no question that the invention of the wheel, language and arithmetic were key developments in the evolution of man. But the "greatest invention of all time" is something less dramatic and still with us today, after more than a million years. It would have been essential and come before fire maintenance. Either the stone-knife or the stone-hammer; then the spear.
Most Respectfully,
R