I have a 2006, original gen macbook. I’ve had similar issues to you.
These machines don’t boot from USB’s in my experience. Burn it to a DVD, you’re issue will probably be resolved. It worked for me. Also, I think your system has a 32 bit UEFI but has a 64 bit processor. This can cause many issues. Personally, I got linux on my machine so I had to use a modded 64 bit linux distro that would work on a 32 bit UEFI. If you want a link to that, I can share it as it would most definetly work on a DVD.
However, Mac OSX is a different story. You have to make sure you’re using a 32 bit distro, aka, the right OSX version. And on a DVD of course, since no boot from USB on that system.