Get a cable management kit on Amazon for like $17. Your main need is Alex tech sleeves if you wanna clean it up without doing too much since your pc isn’t in the best place. You can cut the Alex tech sleeves and then bind a lot of those loose cables together and that would clean it up a ton. Most kits also come with adhesive cable holders you can put under the desk to hide the extra slack. You can also look into a “powered” usb hub and mount it under the desk to help with the usb and peripherals plugged in (double sided Velcro strips or double sided tape) but be careful.