I have numbness in my thumb after hand operation. Is this normal?

Numb after surgery. Immediately after it is quite normal. If it doesn't resolve within 3 weeks, it may take even longer and could be permanent. This depends on the nature of the injury and/or the surgery and is best discussed with your surgeon.
Not usually. If you had numbness to begin (such as carpal tunnel syndrome) and the surgery is to relieve that problem, it may take months to fully resolve; if you never had numbness until the surgery: no, that's not normal and you should tell your surgeon so a proper diagnosis can be made.