The overall meaning of the poem is that people are too concerned with superficial matters of the world, and not enough with what really matters. We are too focused on "getting and spending" and as we do, we "lay waste our powers", or our power to reach our beautiful potential as human beings is wasted.
There is personification in the poem (giving objects human-like traits). Wordsworth says that the "Sea that bares her bosom to the moon", "the winds that will be howling at all hours", and "sleeping flowers". All of this makes nature seem human, real, suffering, sleeping, vulnerable. And, to all of nature's beauty, Wordsworth says that we have become "out of tune."
There are also allusions (references to other stories or figures) when he refers to "Proteus rising from the sea" and "Triton blow[ing] his wreathed horn". This brings up greek myths that can imply everything about the stories themselves in just a few words. He is saying he would rather believe in these "pagan" gods so that he might at least be in tune with nature, rather than being "moved...not" by it as we are now.
Those are just a couple devices to get you started. I also provided a link to a more thorough discussion of the poem itself. I hope this helped!