Yes not only is the human body radioactive, you can actually measure the radioactivity of our bodies with sensitive detectors.

Are our bodies naturally radioactive? - Health Physics Society

Amongst other interesting titbits of information on that page, we eat on average 1/15,000 of an ounce of uranimum every day in our food though only one or two percent is absorbed by the gut - which is then excreted in our urine or our hair.

So we all have uranium in our hair, though some have perhaps a hundred times more than others depending on how much uranium you have in your food.

Most of the radioactivity though is from potassium-40. Much lower amounts from Thorium, Uranium and other radioactive elements.

There's controversial research suggesting that low doses of radiation might actually be good for us, promoting cell repair.

See Could Small Amounts of Radiation Be Good For You? It’s Complicated.