...Cuz every little thing, gonna be alright...
That's what the song says. This is, in fact, true. If you question it, it's because your perspective is too small. You want 'alright' to mean in your time and in your way. No fuss, no muss. (whatever 'muss' is.)
God, of course, has a larger vision, as well as complete knowledge of all that has come before, what's happening now, and what will happen in the future. The whole, eternal future.
Given our limitations with vision and omniscience, it's harder for us to believe that God is working for our good, when we can't see it, or when nothing seems to happen, or when things get worse. Faith is built in these hard times.
Faith, is knowing that God is working everything out for your good, whether you know it or see it or not. He loves you and wants you to spend eternity with him in heaven.
Have faith! Every little thing, gonna be alright!