All the molecules of a substance possess the "average kinetic energy" value.

The statement is not entirely accurate. While it's true that the average kinetic energy of the molecules in a substance is used to define its temperature, not all molecules possess this average value. Kinetic energy, which is energy of motion, varies from molecule to molecule. Some molecules may move faster (higher kinetic energy) and some may move slower (lower kinetic energy) at any given moment. The distribution of these energies is described by the Maxwell-Boltzmann distribution. So, while we often talk about the 'average' kinetic energy when discussing the temperature of a substance, it's important to remember that this is an average, and individual molecular energies will vary around this value.