语感告诉我,你的句子似乎太redundant了.应该是：People kill wild animals for their fur and / or bones.如果一定要解释的话,by在你的句子里解释为“用,凭借”.实话实说,你的句子在表达上有语法错误,因为by是用不进去的.以下是改善了的句子：
People kill wild animals for GETTING bones RFOM their bodies and making clothes WITH their fur.