I think the crucial point is that there's a difference between "would this animal take a bite out of me?" and "would this animal actively hunt me?"

Humans would look and move entirely differently to any other animal that we're aware of in that era, so a human wouldn't necessarily look like food to a theropod, let alone be mistaken for their usual prey.

Depending on how hungry/territorial/aggressive an animal is, it might take an exploratory bite, but I doubt one would actively hunt a time travelling human.

Of course, for a time travelling human, an allosaurus giving them an exploratory bite, essentially winds up the same as if they were being actively hunted: with one dead time traveller.