Jesus is the unsung hero, but frankly they are all sung heroes now. Read the judgement of Jesus and notice how infused with love it is.

BUT the real model for human heroism is indeed none other than Abdiel who openly defies Satan and his cohorts. Abdiel is who Milton wanted us to notice and emulate, surrounded by his enemies and their lies stands up and calls them out for their error and then returns to God expecting nothing leaving the rebel angels to their own and eventually self destruction. Abdiel is also the one who leads the charge against Satan in battle. Stanly Fish makes this argument in his book "How Milton Works" and I agree with him. Satan is horrible, vengeful, spiteful and hate-filled ./spat. Far too Roman. No love.

Another option would be Raphael, though harder to argue, he is the teacher (though incompetent) who instructs and reminds Adam and Eve not to err; noble effort indeed.

Good luck with your paper, the poem is sublime and worth a lifetime of meditation and reflection. One of the truly grand accomplishments of human intellect and imagination ever devised on Earth. Enjoy. Indulge. Open yourself to the poem and grow.