Anne Sexton's poem "Courage" is in a collection that was published after her death.  The poem is a story of humankind's progress from birth to death.  The first stanza is basically saying that one of the most courageous things people do is to take that first step. 

I think the stanza you are centered on is the second stanza which deals with adulthood and life after childhood.  This part of the poem is dealing with soldiers and war; those that return and those that don't. Sexton never uses the term "heroes" but, from the way I read the poem, Sexton really believes everyone who goes about the process of daily living are heroes. 

"If your buddy saved you
and died himself in so doing,
then his courage was not courage,
it was love; love as simple as shaving soap.     25

Sexton speaks of that "buddy who saved you and died himself in doing so wasn't courage, but love." This is courage in action and she honors that act of love.

This poem sort of reminds me of the quote by  Henry David Thoreau "most men lead lives of quiet desperation, going to their grave with the song still in them."  The courageous people go on from day to day with no fan-fare, no accolades, and no notice.  We simply put one foot in front of another without bringing notice to ourselves, and as Sexton's suicide proves she did not have the courage to continue to do this.