As to why Hashem would pay attention to you when there is a whole universe out there: First of all, all that out there was created for Yisroel. We are Hashem’s children; would a king lose sight of his children while running a great land?
But the question itself is actually disturbing. A human can only focus on one thing, but how can you apply the same thinking to Hashem? Why don’t you lose focus of yourself when you become aware that there is a great big universe out there? The answer is because you feel yourself. You are aware of all your feelings. Now, do you think Hashem does not know those feelings?
It says, Ki Ha’adam Yir’a L’Einayim Ve’elokim Yir’a Leleivav. A person sees that there is another person standing in front of him, but has no idea what is going on inside. I noticed that often times people feel that they can describe another person in one sentence. If you ask that describer to define himself in a sentence or two, he wouldn’t know where to start. A person is aware of his own vastness of nature and feelings, but the next guy is reduced to a few twitches and pet peeves. I think that you are applying this viewpoint when you ask why Hashem would focus on you. You have to look understand Hashems view of you like you view yourself.