Without paper, people would not be able to write down what they had learned. They would not be able to have books to keep on a bookshelf because if you had a rock and you spent the time trying to chisel a whole book into a stone, it would take a super long time to chisel and would be too heavy to hold or to send to someone.
The first type of paper was papyrus. Papyrus was made by the Egyptians out of a plant called papyrus. The way they would make papyrus was to cut the plant lengthwise and then they would press the juices out. After that, they would soak the strips in water for a few days. And then they would weave the wet strips together. After weaving, they would press the weave for three days to press out any extra water. Finally, they would let the weave dry in the sun for one day. This would give usable papyrus that you can write on.
I'm amazed at how flat the papyrus paper ends up being.
Here is a video on making papyrus: