There is a reason why Allah had to state explicitly whom we can interact with and whom it is not allowed for us to interact with, whom we are allowed to marry and whom we can’t marry, when and whom we need to have a hijab in front, and whom we do not need this. 

In the time before quran (islam) those souls transgressed into sin and ruined their lives. So Allah had to make it clear for them, how they could save their souls. Ya Allah, protect us from going back to the practice of the time of jahiliyah. Aamen. Ya Allah, help every ummati out of their ignorance into the guidance of Islam. Aamen