On my computer, when itch.io gives me the black human verification screen, it never finishes loading
Well, obviously, you are a robot, pretending to be a human. Nice try, toaster.
Joking aside, you might want to add more details. Like, what browser, or if this is the Itch app, or if you can access sites that use the same protection mechanism. Unfortunately I do not know any examples right now. I sometimes see the same protection, but not very often.
Standard things to try are a new private browsing window, or a different browser. The Itch app had a critical error with that protection for some time. And that workaround here /post/14552731 indicates that the user agent string can break the verification. Some browser addons can change that string.