Two ideas are put. And they are related. First, though sparrows are not highly valued among humans--'a dime a dozen'--God is not indifferent to them. He values them. Second, humans, self-conscious and capable of experiencing God personally, are the subjects of his greater investment and sponsorship. God is the patron of his entire creation but only humans can know and enjoy him. It is principally humans who are addressed in the gospel; humans are the lost whom God comes to seek and to save.
I'm busy working on my blog posts. Watch this space!