Is there any social media without memes and US politics?

As others have said, the best way to do this is to use a platform that has good block list features (most Fediverse platforms qualify), and then curate your block list. You can block users, communities, and instances you don't wish to see here on Lemmy. Mastodon might be for you, because you can also block keywords (Mastodon and Lemmy will happily talk to each other, so you can subscribe to Lemmy communities from a normal Mastodon account and post simply by mentioning the community, or comment by replying to an existing post).

The whole point of the Internet has always been to spread memes.

Because the Internet is a communication medium, and communication is made of memes. I'm not joking. Words, language, music, and art are all memes. (The concept of memes is also a meme). Before the Internet, there was ARPAnet, email, IRC, and BBS boards; all about communication, and thus memes.

Before that, there was the phone network. Before that, the post office. Before that, books, pamphlets, and people telling stories down the pub or around the campfire. All memes.

In fact, this very post is made of memes. The previous sentence contains at least nine memes – the words In, fact, this, very, post, is, made, of, and memes. But there are more memes in there. The phrase in fact combines the words in and fact to make a new meme – in this case, when those two words combine, it asserts more forcefully that the overall statement is true. There's also the spaces between the words, which makes reading the sentence much easier. Yes, believe it or not, spaces between words is a meme. Before the 8th century AD, WORDSWEREWRITTENINALLCAPSWITHNOSPACESBETWEENTHEM. Alcuin of York, a scribe and poet at the court of Emperor Charlemagne, came up with the ideas of lowercase letters and spaces between words to make reading easier, and his ideas were so popular that they spread across most of Christendom. Those memes were so successful that people think of them as natural and obvious parts of (alphabetic) writing, but they aren't. They aren't even a millennium old.

Writing is another meme, going way back to the Stone Age, and it has evolved and developed into numerous other memes, such as the Roman alphabet (which I am using right now), Arabic script, Chinese characters, the Cyrillic alphabet, Brahmic script, Ge'ez alphabet, the Greek alphabet, Cherokee script, Egyptian hieroglyphics, and many others.

Asking for social media without memes is like asking for food without proteins, fats, or carbohydrates. It's like asking for sunlight without electromagnetic radiation.