What happens when there is a continuous effect stating "All lands are creatures," and a land enters the battlefield?

When a continuous effect states "All lands are creatures," it changes the intrinsic characteristics of all lands on the battlefield. This means that every land becomes or is treated as a creature in addition to its other properties.

When a new land enters the battlefield under this effect, it will enter as a land, but because of the continuous effect, it also immediately holds the status of a creature. The rules state that when something enters the battlefield, it exists in the state defined by any active continuous effects at that time. Therefore, since all lands are creatures due to the effect, the newly entering land will be both a land and a creature.

This dual status aligns with the game rules regarding how a permanent is defined upon entering. The transition in status does not prevent the land from entering; rather, it enhances its identity to include being a creature. This is why it is correct to say that the land enters as a creature, alongside its inherent qualities as a land.