Shutter Priority is a Great Mode for Beginner Street Photographers
‘When you select Shutter Priority, it is important to know that, whilst you have full control over the Shutter Speed, the camera will pick the Aperture. What Aperture the camera chooses is dependent on how slow or fast the Shutter Speed that you have chosen is, and also how low or high your chosen ISO, is.’
The Definitive Guide to Shutter Priority for Street Photographers
In my opinion, Shutter Speed is the most important element of street photography - you want to be able to freeze the action, freeze your subjects, or blur them, and shutter speed is the answer, giving you all the control you need to do so.