Enslaving the people of Egypt had nothing to do with sin.
I believe that's what the story is really about.
We both know the Israelites lived in pleasure in Egypt before enslavement. We also know over time, they began worshipping the gods of Egypt. And we also know sin is pleasureable for a while, until we discover how it damages us. Plus, it says of Moses he refused the pleasures of sin.
The NT isn't concerned with slavery, except where our spiritual condition is concerned.
Joseph was a man, with all the failings of a man. We were made in the image of GOD, but we are not GOD. You're mixing the New Testament teachings with Old Testament history.
I didn't imply Joseph was God, or infallible, or that we are.
My belief is that Joseph is a picture in certain ways of Christ. We see our Lord in other believers all the time, because Christians are being conformed to his image.
His brothers said to him, “Do you intend to reign over us? Will you actually rule us?” And they hated him all the more because of his dream and what he had said. Gen.37:8
But his citizens hated him, and sent a message after him, saying, We will not have this
man to reign over us. Lk.19:14
There are many aspects to Josephs' life that mirror our Savior, as we all should.