I can find my husband's iPhone under Devices, but cannot see him under People

He has to specify which device on his Apple ID account he wants to be associated with. On the phone he should go to Settings/[his AppleID name/Find my iPhone, turn on Share My Location, then tap Use this phone as my location.

In order to add him to the people tab you have to invite him from a text message or just add it manually from find my app

Do you share an Apple ID with him?