The answer is: They didn't know what had happened to Moses

Exo 32:1

The tale of the golden calf is a fascinating and illuminating episode in the story of the Israelites' journey from slavery to freedom. As Moses ascended Mount Sinai to receive the law, a vacuum of leadership emerged among the people below. Faced with uncertainty about Moses' return—he had been up there for quite some time—panic and doubt took root in their hearts. Remember, they had just been delivered from Egyptian bondage, but after generations of oppression, faith didn't come easily.

In their disarray, the Israelites whipped up a nation-wide impromptu venture to craft a tangible representation of the divine—a mold made by Aaron from their gold jewelry. Ironically, this was their first major act of free will outside of the restrictions they’d suffered in Egypt. They knew of God, but without Moses' guidance, their steadfast faith faltered. Here, panic led to what might be considered the ultimate "spiritual shortcut."

This golden calf, a symbol likely derived from Egyptian culture where bulls were often venerated, became a way for them to grasp the intangible. It’s related to another twist within the narrative—the juxtaposition of fidelity to the invisible God versus the craving for visible assurance. Like humans throughout history, their craving for something concrete to hold on to illustrates the struggle of faith in the face of confusion and unknowns.

Plus, throughout the Bible, God continually navigates the terrain of human needs versus divine promise, highlighting the cyclical battle between belief and the need for signs. Thus, reflecting on the calf's story reverberates out toward what drives human connection to the divine—even a misdirected sense of assurance. Fascinating, isn't it?