Wow. I love this poem, it's very dramatic and dark whilst also holding out a slither of hope for the world - very well written indeed. I love the ABCB scheme you have going on for the rhyming couplets, it adds a nice rhythm and sense of certainty to the poem. I would recommend perhaps using a few more commas throughout to add some dramatic short-pauses to separate important ideas and emphasize the poem's emotions. A few areas I wasn't sure about:
"Told through agonised cries." = is "agonised" too many syllables here? Maybe a word such as "searing" would fit better.
"With bravery he steps forward" - to me whilst reading and re-reading the poem, this line felt out of rhythm with the rest of the stanza, although I may have been reading it differently than you intended.
"The population of heroes in zero." - I think the word "in" should be "is"?
"So powerful, yet so humble." - this is more of a suggestion, but maybe "and so humble" would emphasize the hero's importance more?
"So many may fall, But few may rise." - this seems to me like bad English, maybe replacing "but" with "whilst" would be better?
Over all a very good poem, I'd love to see more of your work at some point in the future! ^^