Is there a contrast in "God's Grandeur" between human activity and the grandeur of god?
Most definitely. Consider the first stanza of this incredible poem. Consider how there is a divide between the first three lines and the next word and the rest of the poem, which describes man as being divorced from the beauty of nature and how it displays God's grandeur and majesty. Note the following quote which develops the analysis of man and the contrast with nature and how it evinces God's majesty:
Generations have trod, have trod, have trod;
And all is seared with trade; bleared, smeared with toil;
And wears man's smudge and shares man's smell: the soil
Is bare now, nor can foot feel, being shod.
Consider the mindless monotony conveyed in the repetition of "have trod." The internal rhyme of "seared," "bleared," and "smeared" serve to reinforce the way in which man has, through his activity, maligned and defaced nature and the way that it displays the grandeur of God. Man has literally defaced nature and its majesty, and the way in which our feet are now "shod" even prevents us from having the most basic and intrinsic contact with nature. This of course is compared to the description of God's grandeur in the first few lines and the way that the second stanza explores how, in spite of mankind's best efforts to indelibly impose itself upon nature, "nature is never spent."