A hero is a person who is held in high regard or glorified for his or her bravery, accomplishments or dignified values. In my opinion, both Don Quixote and King Arthur are indeed heroes, since they are corageous noblemen who achieve significant successful acts. First, Don Quixote is a poor horseman who believes himself to be an aristocratic knight. Motivated by an honorable willingness to do good deeds, he looks for helping the unfortunate and those who are in trouble. Thus, he engages in a number of entertaining misadventures.
On the other hand, King Arthur is a legendary character who fights Saxons invaders. As a result, he helps to establish the British Empire. He also encourages knighthood, so in his Round Table he only accepts brave, reputable noblemen who love their country and respect everyone. For all these reasons I think both Don Quixote and King Arthur are heroes who represent the ideal gentlemen. They are distinguished men of noble birth, willing to perform fair achievements to do justice. 
 
        
             
        
        
        
The mood of the poem, I don't know because I don't know what the poem is. But, you can find the poem by reading it. If it is like this:
The world is covered in pitch black.
And as I walk, I don't look back,
I'll never return, I'll go on my own.
The world is covered in pitch black.
It seems like a somber and quiet poem. But if it's like this:
We jump up and down ready to go
See our new gift, see our new toy.
We arrive, and I scream with joy.
At our new gift, at our new toy.
Its more like a happy and cheerful poem. Hope this helps!
AYE SIR!
        
             
        
        
        
can you specify the play you're talking about