It is impossible with this image alone.
It is because there is no information "What is the terrain of the tile?"
Tile config data is required.
(Tile config is the data that determines whether the tile is a floor, a wall, or a village , or etc.)
If there is a ROM on which the map actually work, you can extract the necessary information from it.
Please open that ROM with FEBuilderGBA and export tile config and tile set image from Map Style Editor.
I want to explain a little more.
Tiles other than the tile on the upper left are painted with black or red in a single color can not pass.
It is because it is set to Tile Config as a tile that can not pass.
Suppose, for example, we write a picture of a floor on a wall tile.
Although it looks as floor, it can not be passed because it is registered as a wall by Tile Config data.
We have to edit the Tile Config data and register it as floor again.