In Doom, < and > are strafe, and it works here too.

Thanks, this was impossible without strafing, and very easy with it.

Managed to complete the CAPTCHA without strafing but it took me 3 tries.

I was able to do it without this, but this made it much easier. However, it would be much better if the strafing keys were on the left side of the keyboard. You can bunch your hands together and use your left hand for <, >, and space, but it's awkward.

They are, kinda. The default Doom keybinds have ctrl as the fire key, space as the "use" key, and alt as a modifier that turns left/right arrows into strafing. So when you play like that, your left and right hands are separated.