Why Does The Doctor Only Travel With Present-Day, Human Companions?

Coronation Street's Millie Gibson has been announced as Doctor Who's newest companion, Ruby Sunday 

who will travel alongside Ncuti Gatwa's Fifteenth Doctor when he debuts in his first full season in 2024.  

Gibson's introduction into the world of Doctor Who continues a trend 

that started with the revival of the series in 2005 

succeeding some iconic companions such as Rose Tyler, Donna Noble, Amy Pond, and Yazmin Khan.  

the majority of the Doctor's companions have been modern-day humans characters in a change from the classic run of the series 

which featured several alien characters and humans from other time periods as the Doctor's companions. 

some relatable characters and allowing viewers to imagine themselves traveling with the Doctor.