What are the most substantive differences between humans and other animals?”
Humans have the ability to think logically (most of the time) and compose thoughts in time sequence. This is the reason we can use language. Animals can associate concepts such thirst and water but are limited in their ability to associate several concepts or place them in sequence. Some animals can stand upright temporarily but cannot sustain that posture for a long time. Women are receptive to sex almost all the time. Children are completely helpless when born and remain dependent upon adults for many years. This makes women dependent on a social structure to raise their children. Bad backs! Able to commit suicide. Need to cook almost all food.