There is no such thing as an absolutely non-conductive object, it's just the ability to conduct electricity. When a voltage is applied to such an object, a small current will flow through it. As the voltage increases, the current will also increase.
When a person stands on the cement floor, the electric potential can be considered zero and touches the live wire. The voltage from the live wire to ground is added at both ends of the series circuit between the live wire. person and cement. At this time, although the resistance of the cement floor is large, the current flowing through the human body still reaches the tolerance limit of the human body, so electric shock will still occur.