Black bears, particularly the small Florida blacks, are typically very shy. Most people consider themselves lucky to ever see one in the wild. At the first whiff of humans they usually flee before anyone sees them. The few cases where they attack someone almost always had to do with their being abused and/or cornered or having cubs to defend.

All wild animals are dangerous and bears, even the smaller, shy black bear, is fully capable of ripping a human to shreds.

Grizzly bears are a completely different level of potential aggressiveness and danger. But, as I understand it, even here the majority of the cases had to do with the human component doing something stupid. Something simple like carelessly hiking through dense brush in bear country and startling the bear at close range. Or something really, really dumb, like trying to hand feed the bear.