Is chitin actually protein?
Chitin and protein are completely unrelated. 
The only common thing is that they are polymers. 
Chitin is a polymer of amino sugars while protein is a polymer of amino acids. 
Both monomers are very different and are not converted one to the other. 

In fact, chitin, like cellulose, is not fragmented by animals, so it is not absorbed. 
Moreover, chitin is a homopolymer, so even if it where absorbed and transformed to amino acids, it would yield only one (or maybe a few ones) but all the others would have to be obtained through a different source. 

So chitin is not a source of protein or amino acids.