If you are asking for an analysis of the meaning of the saying, "We do not inherit the world from our ancestors but we borrow it from our children," we first need to look at traditional ideas of inheritance.
Inheritance is a means of passing wealth from one generation to the next. Generally speaking, the focus of any given generation is on the use of what they receive from the prior generation, not what they are passing on to the next generation. Thus, we may speak of inheriting the world—for our own use—from our ancestors.
This traditional idea of inheritance, where the wealth left was for the benefit of the next generation, is in contrast with the idea of holding wealth in trust. When wealth is held in trust, the person holding it, known as the trustee, may use it but must do so primarily with respect to the benefit of those for whom it is held in trust.
In the saying referenced, the idea is that each generation should not view themselves as the inheritors of the world but rather as trustees of the world for future generations. This focus helps foster concepts of stewardship and sustainability over ownership and short-term usage.