If you’re still curious we did not start working glass for its transparency. It was most likely started as a sanitary concern. Glass is easy to clean with soap and water, once it’s cleaned out you can use it again for anything and no germs or flavor from the previous meal or drink will remain.
Other materials at the time, namely clay, would absorb flavors and germs meaning that if you ate beef off a clay plate your next meal with that plate could have beef flavor and microbes common on cow meat on it. That would leak out seemingly at random no less. Heck imagine a sick person coughing into their soup bowl and then months later their germs hiding in the clay would pop out to infect whole new people.
Also the earliest human use of glass we know of is for its sharpness. Pre-historic people would use volcanic glass as sharp knives for food preparation. Also beads. Pretty much any new substance humans get their hands on for most of our history we immediately try to make into beads.
The fact that it could become see through was a side benefit.