What is more dangerous: an untreated human bite or an untreated black widow bite?

That depends.: A human bite can cause tissue injury & infection. A black widow spider bite may cause a minor reaction or a severe one. People rarely die from the bite of a black widow - but most deaths that do occur are in the elderly or in infants. So - there is no one -size fits all answer to this. Each human bite case & each black widow bite case are different.

Bite: Depends on the extent of the bite, your general health & status of your immune system, & your age.