The question of existence ( why live? ) has only some intersection with the question of morality ( why be kind? )

On the side of the existential question, some folk find it enough to find a place to fit into society and serve a roll. At least this was the position of Jean-Paul Sartre, hence the notion of existence precedes essence. To me this compares too readily with the notion of interchangeable parts, as our industrialist masters are glad to force us to work for them as a component in their big productivity machine only to be discarded when we wear out. I digress, but maybe we shouldn't let industrialists dictate the missions of society.

In my experience, all my occupational ideals were discovered to be toxic or driven by racketeering. Most music is stolen by the big labels. Game development is run by executives looking to make microtransaction skinner boxes, and gladly crunch their teams even when doing so has been shown to kill productivity. Navy advancement is based on what rich people and government officials you personally know. And so on. Having talked to others, it seems like there's a lot of anecdotal evidence that every occupational dream is quashed by grisly realities that are unnecessary but for our love of dominance hierarchy and doing things half-assed to maximize short-term profits. I have a lot of resentment of capitalism and how it's done in our society.

But I got really crushed once it became evident we weren't going to respond to the climate crisis in time, if at all, and we expect a population correction, late in my life. It may lead to human extinction in the next couple of centuries, but it absolutely will rend asunder any human culture, so whether I made music or discovered better scientific models or even wrote a sweet novel that was classic material, it wasn't likely to survive the upcoming global famine.

But this is similar to where Albert Camus was after WWII, recognizing the absolute meaningless of life and the inevitability of death. We all come to this crux, where we have to choose how to proceed from here, knowing that life is pretty awful, pretty meaningless and pretty temporary.

• You can kill yourself. It's where you're going anyway. (I don't recommend this mostly because it is really harsh on people close to you and some people that aren't. Still, our suicide rate here in the states is high thanks to the crappy state of the economy and rising hate politics.)
• You can commit philosophical suicide by taking a leap of faith. Christianity offers a personal Jesus and the prospect of eternal life in Heaven, so you don't have to concern yourself with the grim reality of mortality. That said, all the ministries are a sham that will parasitize you much like any industrialist or employer. Heck, pre-resurrection Jesus had a few things to say about this is the case and one should follow their own path to ~~enlightenment~~ spirituality.
• You can deal. Dealing with aplomb (that is, leaning into it and embracing the absurd mission of finding meaning in a meaningless life) is harder than it sounds, but so long as you don't take either of the other options, you're actually doing the thing, even if not with grace and poise and a perfect landing.

That said, tacos is as perfectly find a reason to continue onward as any other, an example of a hedonistic approach. I find my cat sometimes provides me with enough cause without further explanation. On the other hand, I do have a desire for my own legacy, not future generations, but of contributing to the body of human knowledge, art and technology, and I can't be sure anything in my fields of interest are going to be useful once the ecology fully collapses.

Atheism, in my experience, is coming to terms with bad news: We're going to die. The odds are against our becoming significant in the universe. We're not even a particularly happy species or society, and while I'd like to imagine we'll overcome some of these with technology, say some sociological tricks that allow us to curb corruption and move towards egalitarianism, it's much more likely we're just going to go extinct, and let some other critter evolve social brains and have a go at reaching into space.

In that regard, religious faith is at hubris that we are bigger fish in a smaller pond, and at best a cope rather than confronting how tiny we microbes are in a vast unending ocean.