Jizo Statues contain many vital mechanics necessary in the game.
First off, you can use them to quick save your progress. That way, it won't be necessary to save in the diary in the Home. It is fortunate that there are several Jizo Statues scattered throughout the map.
Second, they act as a respawn point when you are killed. When you die, you will respawn in the last Jizo Statue you quick saved. However, if that last Jizo Statue you quick saved is before your last Home visit, then you will end up respawning at Home.
Third, the Jizo Statues act as teleporters for the player. They are used to help the player to teleport to different areas throughout the map. This make moverment easier.