Even car drivers are pedestrians at some point, but in a city, it's quite easy to be a pedestrian and never be a car driver.

So more practical than banning pedestrians would be banning privately driven cars. Commercial trucks, emergency vehicles and taxi's/Uber/Lyft with appropriate driver standards/training requirements could still be allowed on roads.

Drivers that really want a private car could keep them parked outside of the city center, or maybe they could pay for the same driver training/certification of commercial drivers - and all drivers should be held to very high standards, no more "I didn't see him in the cross walk!" excuse when a driver hits a pedestrian.

I don't make enough money to "own" a car. It's dangerous, stressful, expensive. The car becomes a single point of failure that can turn my whole life upside down if it ever fails, which cars often do at the price range I can afford. Banning pedestrians would basically ban poor people from going outside.