That is not always the case, but it seems to be among the most common ways people are considered for heroism. Because Moses and Krishna were not heroes in the traditional sense, however, does not in any way negate the value they had to their respective time periods and the information that was written about them. Being a hero can come in so many different types of forms, that anyone can be a hero in some way and an amazing, courageous act is not always required. At times, all that is required is for the hero to do small things, but to do them with such love and consideration that they become big things in the grand scheme of the world. While not everyone understands this concept, most people who have seen these kinds of heroes at work are aware of what they can do and what they can offer to others...

Most people do not start out wanting to be heroes, but they are required by circumstances to change what they are doing in order to help themselves or someone else - and in that process they often become heroic.
References

Bhagavad-Gita (Books 1, 10-11). (n.d.). http://www.bhagavad-gita.org/Gita/intro.html

Coburn, T.B. (1984). 'Scripture' in India: Towards a typology of the word in Hindu life. Journal of the American Academy of Religion 52(3): 435 -- 459.

Exodus. Chapter 19-22. (2012) the King James Bible.

Houston, Walter J (1998). Exodus. In John Barton. Oxford Bible Commentary. Oxford University Press.

Sandars, N.K. (2006). The Epic of Gilgamesh. NY: Penguin Epics.