Why do we say sunrise and sunset?

They were named before we knew that the Earth rotated.

Because we state what we see. Although the Earth revolves around the sun, due to relativity we revolve with it and the virtual image of the sun makes it appear to rise and set. By the same token the moon revolves around the Earth so we also get a moonrise and moonset.

Okay smarta$$, explain to the world what they should be called and we'll all immediately change and take the romance out of them just for you because that's what we live for, making you feel like a genius.

Because most of us aren't literalist drones like you. I bet you don't like poetry or art, either.

Figure of speech.

Because of THAAAAAAA GEEEEEEEEEE OOOOHHHHHH PEEEEAAAAAAHHHHHH!!!!!

#1 Old habits die hard. When it was discovered that the Earth rotated and was NOT the center of the universe, people who made such claims were persecuted as heretics. For thousands of years, humans believed that the sun was rising and setting.

#2 From our perspective, we do detect the movement of the Earth, therefore we see the sun as setting and NOT the planet's rotation.

#3 It sounds nicer: "What a beautiful sunset." vs "What a beautiful rotation of our position on the Earth's surface as we transition from sunlight into the Earth's own shadow."

Because that's what it look like. There's nothing mythical about it. You can watch it rise in the morning and set in the evening.

Horace, Egyptian god of sun fought with Set, Egyptian god of darkness. At night Set would best Horace and the sun would go down and Set would rule.