https://en.wikipedia.org/wiki/Chitin#Humans_and_other_mammal...
People do eat mushrooms and shellfish, after all.
Larger insects can have their exoskeletons removed or partially removed, and those can be turned into chitosan, just like the shells from peeled shrimp.
It seems likely to me that people with latex-fruit allergies would also be allergic to the breakdown products from non-human chitinases, whereas those with shellfish and dust mite allergies would also be allergic to the breakdown products from human chitinase. Either way, it is likely to be a food allergen.
There is tons of research demonstrating the immuno-moduating effects of mushrooms and yeast.