hero to humanity

[masterding]

Quotes from VOA news:
Revered civil-rights leader Reverend Jesse Jackson greeted reporters before his formal remarks, saying King’s fight must go on. “We have the obligation to not just glow in this but to keep raising the challenging and disturbing moral questions of economic justice and fairness," he said.

Stevie Wonder added to the chorus with his song, and members of King’s family orated, including Reverend King's sister, Dr. Christine King Farris. "I witnessed a baby become a great hero to humanity, who provides hope and inspiration for freedom-loving people everywhere," she said.
....

But the day’s big speaker was no doubt U.S. President Barack Obama, the nation’s first black president, who was just six-years old when King was assassinated. “Because of that hopeful vision because of Dr. King’s moral imagination, barricades began to fall and bigotry began to fade. New doors of opportunity swung open for an entire generation. Yes laws changed, but hearts and minds changed as well," he said.
MY questions are:
1. I have some difficulty understanding the sentence "We have the obligation to not just glow in this but to keep raising the challenging and disturbing moral questions of economic justice and fairness," what message is he trying to convey?
2.hero( to )humanity ,why not hero for humanity ?
3. what does "moral imagination" mean?
thanks.

[birdeen's call]

1. I have some difficulty understanding the sentence "We have the obligation to not just glow in this but to keep raising the challenging and disturbing moral questions of economic justice and fairness," what message is he trying to convey?

Instead of resting on their laurels, they should keep asking difficult questions about morality in economics.

2.hero( to )humanity ,why not hero for humanity ?

You are something to somebody. That's just the way it is. For example:

He was a brother to me.

3. what does "moral imagination" mean?

I don't know.

[SoothingDave]

Dr. King is famous for his "I have a dream" speech in which he outlined a vision of a world without color barriers. Where a man is judged not by the color of his skin, but by the content of his character.

That is what I imagine the "imagination" refers to.