Acompany charges $5 for its product. this monetary amount represents the of making an extra unit of the product.

In this case, that monetary amount represents the marginal benefit. This is defined as the amount of money someone is willing to pay to consume an extra unit of good or service. Usually it increases as a person consumes less and vice versa. We can understand this part by thinking that every time you use a product the value of the following one diminishes.

There si no reason to consider Europeans as heroes. In the history of mankind, while many important achievements have been developed and designed in Europe, there is no reason to believe that this means people from Europe should be considered heroes. There are also parts of European history (colonization) that are not very hero-like.