How does copyright work if I completely produced, composed, wrote lyrics, and even sung demo vocals?

[ethanchaz]

As the title says, I've completed an entire song and only want a female singer to record her own version of the vocals. I am not wanting them to change or improvise at all. I am a capable singer so I provided my own vocals to completely copy. In this circumstance would it be acceptable for me to completely own the entire song? I have no following but  I'm a music major and want to use this as a demo so I can gain experience and credibility for peers I hope to collaborate with.