Where did the oldest alphabet come from? Why is there much less signs in it than in the cuneiform

Where did the oldest alphabet come from? Why is there much less signs in it than in the cuneiform and writing of the ancient Egyptians?

Scientists today believe that the oldest alphabet originated in Phenicia. It was a significant step forward compared to the then existing writing systems. In Egypt and Mesopotamia at that time, hieroglyphic and cuneiform writing were used, respectively. Therefore, there were a lot of symbols in them. And in the Phoenician alphabet, letters symbolizing sounds were used instead of hieroglyphs denoting any individual objects. Therefore, there were significantly fewer symbols in it.