If i get bight by someone on my hand why i can't feel the inside of my thumb?

Neuropathy: They may have clipped a nerve, or the swelling from the inflammation from the bite may have produced pressure on a nerve. Human bites are more prone to severe infection than many animal bites and would strongly advise you to see a doctor (hand surgeon if available) and get this examined asap.

Digital nerve: Could be a neuroapraxic injury to digital nerve supplying the thumb, or even possibly the nerve being severed with the bite. Seek care with hand surgeon.

Digital nerve: Could be direct injury or secondary to swelling, but appears the medial digital nerve branch has been affected. Since human bites can get complicated by staphylococcus, wise to have your physician evaluate.