One thing I learned long ago...when discussing subjects across cultural/religious lines you MUST define your terms!
A quick read of the Bible where "slaves" are discussed will show the reader the biblical concept of slavery would be better described as "contract employment" in today's terms. (It was neither permanent, nor absolute) That as opposed to the "chattle slavery" practiced in Islamic circles and early America.
Now I can't say if early Israelis actually practiced the biblical version of slavery, just as they ignored the "sabbath for the land" for so long, but that's not the Bible's fault.
The short answer to your question is...depends on how you're defining "slavery."
BTW...what makes you think we're "grown up?"