Because we kinda like to figure out how the universe works rather than just beg the rain gods to spare our harvest. You know all that great stuff that makes your life awesome, like this internet thing and all of the cheap food and clothing and cool gadgets and all that stuff that makes your life good? That came from the people who weren’t satisfied to not figure out how things actually work.
As for god and evolution. Sure, you can think both happened, and lots of people do. It’s a less ridiculous position than thinking evolution didn’t happen, because at least you’re accepting reality and not thinking god planted the dinosaur bones 6000 years ago to fuck with us.
But it’s also sort of useless. It adds no explanatory power, it’s just like saying “ok, so evolution happened, but god did it!” “Ok, so the universe is huge and expanding, but god did it!”, etc. Basically, just stating what actually exists, and then saying “god did it!” adds nothing to the explanation. God isn’t necesary to the explanation, nor does his presence actually help explain anything. What’s the point?
The reason idiots really want to deny reality though, is this: the entire point of inventing gods is to explain things you don’t understand with an idea that gives you a sense of control. Back when we didn’t understand how the solar system work, or how weather worked, we had the sun god that pushed the sun across the sky, and the rain gods who would reward or punish us with good weather for our crops.
As we learned more and more about how things actually worked, those explanations for god became unnecesary. We no longer need sun gods or harvest gods, because we figured out how those actually work. Well - it used to be that we couldn’t explain the biodiversity of life and how we got here, so we used god to fill in that gap. He gave us all the animals, custom designed just for our world, and he created us, super special humans, in his image.
That’s part of the issue actually - it was easy enough for people to give up the idea of a sun god or weather gods or gods of the sea because we don’t have that much invested in it. But the idea that humans are super special, unique from anything else in the universe, custom-designed by god, is a big ego booster. To think that we’re just a rather remarkable result of random processes, same as anything else, is a big hit to our ego. It’s a lot harder to give up the idea that you’re the most special thing in the universe than to give up sun gods and sea gods and harvest gods.
Evolution removes the need for god in the explanation about life just in the way that our understanding of the solar system removed the need for the sun god. Sure, you could still say “ok, so the sun is at the center of the solar system and we revolve around it… because that’s how the sun god wanted it!” but at that point, what role does the sun god serve in your explanation? Why is he necesary?
Similarly, once we figured out evolution, what use is the modern monotheistic god in explaining that? Saying “evolution happened exactly as it appears, and would be logical to happen, but… god did it!” is equivelantly useless to saying the sun god wanted the sun to be at the center of our solar system all along. It lacks explanatory power and is unnecesary, it’s just special pleading to maintain the beliefs you find most comfortable.