Why were the people of Jericho wicked when they'd never heard of the Hebrew god seems like hypocrisy to me?

It depends on which book you're reading. If it's The Bible, then the people of Jericho were wicked. If you're reading the Books pf Jerichoeans, then it's the Children of Israel who are the wicked for destroying their cities, massacring all the menfolks and womenfolks including children and infants, but saving the virgin girls for themselves.