Little Lamb who made thee (line 1)
During the 18th and 19th centuries, the development of science led many philosophers to look for a "design" in the universe. From this perspective, people come to know God by knowing his creation, instead of the other way around.
Gave thee life & bid thee feed. By the stream & o'er the mead; (lines 3-4)
Like a kid with a wind-up toy, God gave creatures the means to live and then set them loose to roam around, eating to their heart's content. But the innocent perspective doesn't mention the chaotic, amoral, dog-eat-dog character of nature.
Softest clothing wooly bright (line 6)
The speaker thinks of the lamb not as it relates to nature, but as it relates to human society and its needs. He regards the lamb's wool as "clothing," like a really nice sweater.