No, because it is obviously a derived work. It's extremely unlikely someone who never heard the tune "Happy Birthday" would come up with lyrics for the (non-cop

No, because it is obviously a derived work. It's extremely unlikely someone who never heard the tune "Happy Birthday" would come up with lyrics for the (non-copyrighted) melody that sound exactly like the copyrighted lyrics by sheer coincidence. You could, however, use entirely different lyrics. But I'm pretty sure it could still be assumed to be a derived work as long as it's a birthday song. Disclaimer: IANALATINLA, etc