My laptop came with Windows 11 installed and I hate the look of it, so I decided to customize it. This is what all I have done!
The most important thing I use is a program called StartAllBack (or StartIsBack if you use Windows 10). It lets you customize the task bar, start menu, and file explorer. You can choose between the Windows 7 10 and 11 versions of each and customize the colors of the task bar and start menu. There is a 100 day free trial and after that there is a one time purchase of $5 if you want the activation license. It's definitely worth it. It technically still works without the license after the trial ends, but the color customization doesn't work and there is a sad face on the start menu. Here is the link if you're interested: startallback.com
I have custom Hello Kitty cursors. You can do the same, just search for a cursor pack that you like, download it, and put all the .cur files in to the C:Windows/Cursors folder. Then go to settings < mouse < additional mouse settings < pointers, then go through and change them all. There should be one for each cursor type (normal select, working in background, text select, etc.). Click apply and it should work.
I also have pink window borders and title bars. You can do this by going to settings < personalization < color < accent colors and select the color you want. Then check the box that says "Show accent colors on title bars and window borders". Obviously there are tons of other things you can do in the personalization settings, but I'm going over the most important ones I use. My desktop wallpaper is a pink version of the classic Windows 7 background.
I hate the new folder icon so I have custom folder icons on my desktop as well. The old folder icon used to be in the directory with the rest of the Windows icons but they removed it at some point, so I had to find an image of the icon and convert it to a .ico file. You can do this with any icon on your desktop. Right click < properties < customize < change icon and find the .ico file you want to use. If it is a program shortcut, change icon will be under the shortcut tab in properties.
This isn't necessarily a Windows customization, but I use Brave browser. I have found it to be the most secure and least intrusive browser that I have used. The new tab page is very customizable. You can choose to have absolutely nothing on it if you want, and it supports custom backgrounds just like most other browsers. It has a built-in ad blocker as well. You can use most themes and extensions that are available on the chrome webstore too. I have also found that it isn't quite the memory hog that other browsers are. And oh god is it better than Edge. Anything is better than Microsoft Edge.
I hope I encourage at least someone to customize their Windows computer a little. It's really fun and not very hard. If there is any way that you customize your computer that I didn't mention, put it in the replies.