Finished product, each piece is ~1×2 and oiled with linseed oil. Thanks to everyone who suggested those things. I don't like stains with artificial coloring, but I think the oil brings out the character of the wood and gives it a finished look. After watching TV at that height for a week. I like it. I want to lean back and look slightly up to it.
This is what it looked like last week, I posted it on Reddit and everyone said it looked like a giant pallet, and that I should stain it or oil it. Some people sent pictures of other walls like it and I really liked the look of the thinner boards, so I decided to change it.
I took each piece down, and ripped it in half.
Apparently I don't know how wood works, because this was crazy to me. This was a relatively straight piece that I ripped down the middle, and now the pieces bow apart from each other.
I figured, since I'm going to all this trouble, I'll sand them this time around.
Then I applied boiled linseed oil. I just poured some on a rag and wiped it on. Since it soaks into the wood, it's pretty hard to do it wrong or unevenly. I was just liberal with it and it worked fine.
I figured out the distance they need to be apart for the new pieces to take up the same amount of space, and I cut new spacers.
I started at the bottom this time. Being able to rest each new piece on top of the ones below it was nice.
Getting there. The process was a lot slower this time. Sanding, oiling, and then putting back up twice as many pieces. In this picture you can see the color difference with and without the oil.
TV was taken down and put up asap so my wife could watch TV while I worked. TV back up.
Finally. Finished. If you look closely, the gaps at the top are a little uneven. That took a few adjustments but I think it worked out.