No, if you have Medicare, you’re considered covered. Just mark that you had health insurance all year and that's all you have to do on your tax return. Your Humana supplement is not a Healthcare.gov plan.
"The Marketplace (Healthcare.gov) doesn’t offer Medicare supplement (Medigap) insurance or Part D drug plans." For more click here on HealthCare.gov.
It’s against the law for someone who knows that you have Medicare to sell you a Marketplace plan.