I don't object to using a better word where a better word can be found, or to making messages as straightforward as possible.

However, I think most Internet users know what a CAPTCHA is. And even if they don't know what they are called, they have probably completed them before, and so inherently understand the task required. And even if they have never completed one before, they are designed to be human-solvable by someone who's never encountered one before.

So, I fail to see what the problem is. Close the task?

For now I oppose what proposed in this task.
(1) "security code" may be easily confused with 2FA tokens. I do not recommand such term.
(2) "human confirmation" looks weird if it is placed inside a sentence.
(3) Changing the term will incurs further I18n challenge, since it may not have a direct equvalent in another language. Chinese have a term for CAPTCHA, and it is non-technical and commonly used. Changing the English term will confuse translators.