We are not getting very far with this. The boot listing you show does not include a USB flash drive. The USB boot enabled is just allowing that to work, but not showing a USB device to boot to, which should show under the Boot Priority Order, or the Boot Device List, which I don't think you have found yet.
Below are two attachments. One is the file structure of a Bootable Recovey Drive you can check against yours. The second in the Boot Device List on my system. You need a UEFI boot capable flash drive, and it appears you do not have one. There are some sites that seem to offer one you can download. As long as it is Fat32 and active, it should work if the correct files are on the drive.