There are exactly 1.6 x 10^18 kilograms of lead on earth but every three minutes or so a brand new gram is welcomed into existence due to the radioactive decay of uranium.
Also, the half life is when half of it decays. Some of it is constantly decaying. We don't need to wait for the half life to see any of it. The ratios would be totally off if there was enough of it to get the amount of lead we have right now, but some would exist. When the math is that complex, it's not going to change anyone's mind who believes what a magic book (written by regular humans) says. Nothing will, be if you want a chance it has to be something simple and obvious.
Some lead might have been created from supernova fusion, probably. I'm not actually sure if it's the right isotope or if lead even has radioactive isotopes that we know of