That said, not all culture is important to all people. To me Notre Dame is interesting only for its architecture. I'm not Catholic, nor even religious, so that aspect of it doesn't mean much.
How have I personally benefited from this building? Just curious. I can't even claim to have read the book that the Disney movie was based on.
That's the kind of missing the underlying canvas which drives me to the wall.
It's irrelevant if you're not religious. I'm a effing atheist too, remember ? Of course if I were religious, it would have additional value as a very important place of worship, and a spiritual value as the house of my supposed god or whatever. But even as someone who sees religion as fairytale, it's still important, precisely because it WAS and IS important to people, because it's a witness of an era, its a creation (and also due to this a creator) of a culture. It's a part of the big canvas that is mankind.
As how you benefitted, short answer : as with all the lasting cultural and historical artefacts, it did just as much to mold you into who you are, and mold the whole mankind into what mankind is, than society did.
And now the long answer :
Think about all you know of Ancient Egypt. You actually probably know more about it than everything else from Egypt put together. When you hear "Egypt", you think about the name of Pharaohs, you think about the Nile, about sands and temple, about Pyramids and Sphinx, about hieroglyphs and tombs, about sun and flood. You think about how they dressed, about their gods and their religion. About the war chariot and the khopesh.
That's quite a lot, isn't it ? That's part of your collective memory of mankind. What they accomplished, how they viewed the world, how their astronomers were actually quite advanced, how their Pharaoh had absolute power, but yet it was not limitless and could be challenged by a weird system of vote with black and white stones.
And maybe you didn't knew all that, but this knowledge still existed, in book and in library, in specialists minds and in some enthusiast circles.
All this past, all this history, all this culture, played a part into making us - all of us, be it directly because we learned about it, or indirectly because someone else knew about it and it affected him and he affected us by his opinions and his existence.
And how do we know all that ? Because of what they built. We know jack of about people that were living on our own lands 4000 years ago, and as such nothing they did and nothing they were, does affect us, nor help us grow, nor even exists anymore.
But we know of these guys from 1500 years further in the past, and thousands km away from where we live, and they affect us, and we can draw ideas and lessons and ponder how they lived and get a wealth of points of view on the world. And that's because they left things behind that acted as witnesses.
And of course we are probably making a ton of wrong conclusions, because it's old and weathered and we are left to fill the blank. That's why it's always such a great find when we discover something intact, or well-preserved, or giving us more informations that allows us to get better ideas of who they were and how they lived.
And I've not even spoke of the metaphysical aspect, knowing there is buildings which were already standing when your forefathers were alive. Connecting people to their past and giving them a sense of belonging. That's stability for a society, and a way to draw strength from the past, and maybe for some people to realize the scope of humanity and get an appreciation from things beyond their own little circle of acquaintances.
So yeah, what mankind left behind as time passes IS effing important and DOES serve us. All of us, even those who are too blind to realize it. And each time we lose one of these artifacts, we deprive our children of such connection and such riches. And that sucks much more, in the grand scheme of things, than even the lives of many people that would not be able to provide such link from the humanity of the long past to humanity of the long future.