Why did God go to the Gentile without the Jews?
The vast majority of Jews rejected Jesus as their Messiah, and they let the ball drop. As a result, God went to the Gentiles without them, opening the way for non-Jews to receive the salvation that is only in Christ.
Les explains that Peter was dealing first with the covenant people, the Jews, who had to recognize that Jesus was the Christ and only Jesus. But the vast majority of them rejected that truth, and as Les says, they let the ball drop. So God went to the Gentile without them. Les also points out that thousands of Jews did embrace Christ early on, and archaeology is proving it, but the nation as a whole refused Him. At the point Peter is speaking, however, they were still dealing with the covenant people, not yet fully turned to the Gentiles.