This poem isn't spoken by one speaker, but by several. It's a poem that asks everyone to join in. In fact, in the fourth line, the speakers explicitly say, "Let our rejoicing rise." It's not "my" rejoicing, or "your" rejoicing; it's "our" rejoicing. This signals the fact that, as a song, the poem is spoken, or sung, by a number of speakers. We're welcomed to lift our voices and sing right along with the speakers.
The implied speakers are African-American, as this is a poem that was written by an African-American poet about the hardships and the hopes of African-Americans. The references to the difficult path that the speakers have walked is an allusion to the oppression that African-Americans have faced in the U.S.
These speakers are very hopeful speakers. They've been through some really hard times, they've shed tears and blood, but they have faith that they're going to come through and achieve their freedom. Maybe we can learn a thing or two from their perseverance (especially when we're tearing our hair out, struggling with poetry).
What's more, these speakers are religious. They believe in God, they love Him, and they want Him to protect them. The speakers have nothing but good things to say about God. For them, the Big Boss is a Good Boss.