The Underdog Project - Summer Jam

Not familiar with said song. I can assume it's not meant to be deeply analyzed academically.

I think you're overthinking a cheesy pop song.

And to be honest, I did have to Google the term pleonasm but I still stand on my assertion that you might be too critical of the songwriter at hand.

Besides, brown skin in terms of the cultural, political, and ethnic makeup of the US isn't a redundant concept as we still are struggling with racism, minorities, and other related social political issues du jour.

Cinnamon tans is probably just a poetic turn of phrase.

Cinnamon tans could be a reference to fake tan, sometimes called orange tan.
Something ghastly like this.