Weaving was probably invented much later than spinning, around 6000 BC, in West Asia. At first people just wove narrow bands with their fingers, tying one end to their belt. That was something like the finger-knitting you might know how to do. It was only later that people began to use looms.
Woman weaving in China
(Of course there are many other uses for thread like tying up your hair or making fishing lines or hunting nets). But suppose you want to make cloth. So you take this thread and you loop it back and forth over a loom to make the warp, and then you weave back and forth through the warp to make the weft, and then you have a finished piece of cloth.
Then you can cut the cloth off the loom with a knife or a pair of scissors and tie off the ends so they don’t ravel (or leave them long to make a fringe).
You might think the main purpose of weaving was to make clothing, and people did use cloth to make clothing. But people also used cloth for all kinds of other things: sails for boats, tents, carpets, sheets, towels, cheese-making, bags to carry things in, and many other things.
You Can Weave!: Projects for Young Weavers, by Kathleen Monaghan (2001).
World Textiles: A Concise History, by Mary Schoeser (2003). For adults.
Women’s Work: The First 20,000 Years : Women, Cloth, and Society in Early Times, by Elizabeth Wayland Barber (1995). Not for kids, but an interested high schooler could read it. Fascinating ideas about the way people made cloth in ancient times, and why it was that way.