For human beings, the abilities to read and write are marvelous achievements. For the several hundred thousand years that humans were living as hunter gatherers, written records do not exist.
It was only in the last ten thousand years or so that humans began to form agricultural societies. Today, human society is primarily agricultural.
Written records exist only from around the last ten thousand years since the shift towards agriculture. On the other hand, humans have been speaking to each other for a much longer time. Hence, much of the ancient wisdom and records were carried in the form of oral recitations from times immemorial. The ancient Indian scriptures called the Vedas were carried on as an oral tradition for long before being written down.
Until a few hundred years ago, before the invention of the printing press, most people could not read texts. It appears that even those who could read usually had to read it aloud and humans learned to read in silence on a mass scale only recently.
Overall, it is remarkable that human beings have consciousness and developed the ability to read and write. At the same time, in the world of today, it has fooled many about the extent of human knowledge. One needs to keep in mind that the intellect is only one of the human appendages. It is not the be-all and end-all of everything.
Nietzsche described those who overestimated the value of this one particular quality in Thus Spake Zarathustra:
And when I came out of my solitude, and for the first time passed over this bridge, then I could not trust mine eyes, but looked again and again, and said at last: “That is an ear! An ear as big as a man!” I looked still more attentively—and actually there did move under the ear something that was pitiably small and poor and slim. And in truth this immense ear was perched on a small thin stalk—the stalk, however, was a man! A person putting a glass to his eyes, could even recognise further a small envious countenance, and also that a bloated soullet dangled at the stalk. The people told me, however, that the big ear was not only a man, but a great man, a genius. But I never believed in the people when they spake of great men—and I hold to my belief that it was a reversed cripple, who had too little of everything, and too much of one thing.