You obviously ask some really great questions because it requires some serious thinking to get back to you!
I think you hit on the answer to your own question when you said that God's existence is questionable and intangible to you. Of course you cannot feel humble toward something you're not even sure exists. And you cannot have that fall-on-your-knees, totally awed type of response when you haven't experienced God for yourself. How could you? It wouldn't make sense.
On the other hand, you stand in awe of nature, of birth, of the cycle of seasons. And those things wouldn't be here without God. I don't think there's anything that we know as humans that is more amazing than nature - waterfalls and oceans, mountains, and canyons. Yet, I believe that God created those things. What a fantastic imagination God must have, what a deep and complex mind, what amazing power to spin all those things into existence! If I am amazed by nature, I must, in turn, be amazed by the God who created it all. ...if that's what I believe - that God created it all.
And the place where I stand truly in awe and humbled by God, is in that the God who made this whole big earth *knows* me, hears me, sees me, LOVES me. God is everywhere, continually creating and calling all of us into existence, holding this whole apparatus together...and, yet, God also has concern for me as an individual...me, so small in comparison to the rest of the world, yet I am held close to God's heart. What an enormous God...to know and love each of us that way.
In some way I believe your husband is right, it doesn't make sense to *try* to feel a certain way. I believe you when you say that you're already living a humble life, a life of goodness and compassion. And, certainly, these are qualities that are pleasing to God. You know why? Because you were created in the likeness of God, in God's image. These are the qualities of God in you. But I don't think this means you can stop seeking. You obviously have a drive to know the truth, to meet the truth, to encounter this God we're all talking about. The Bible tells us that those who seek will find. I can't tell you what that will look like for you because I think God has a knack for meeting us where we're at, in ways that make sense to us as individuals. That makes it different for everybody.
I guess I don't see your feelings of humility , or lack of those feelings, as the real issue. If you know God, humility will follow.
I'm curious about your response to this and where you want to go from here. You may be interested in something called Apologetics if you're truly interested in exploring the existence of God. Apologetics is the part of theology that addresses the existence of God and the historical Jesus. For me, Apologetics is fascinating and an encouragement to my faith, but I don't know if it would have fed my hunger to really know who God is or not. It's a very academic approach to God, providing proofs for the existence of God. If you're a reasoning/rational explanation kind of person, Apologetics may be for you. If you're more about feelings and emotions, maybe not. I know I need both.
I am inspired by your persistence!