The iconic home button has been a mainstay of Apple design ever since the first iPhone debuted in 2007. Even the buttons on the elevators at Apple Park are said to resemble it. The button’s tactile circularity promises an escape route to familiarity should users get lost or apps go wrong.

https://www.macrumors.com/2017/03/05/how-home-button-function-bar-could-work-iphone-8/