Just FYI, I think row 8 is off by a pixel. I created a blank background image to make sure everything is oriented correctly that might be useful for anyone making more tiles. 
And here's a close up of row 8, showing slight misalignment. 
Also couple pictures to show why I organised them in a tall thin column, 8 wide same as original tiles. it was merely because it gave me more space to use the screen, as I'd rather scroll further than be really zoomed out or have to use up the screen with the panel more than I need.
8 columns:
Lots of columns:
I spent ages organising the tiles in a way that made sense to me with just 8 columns but eventually just decided "good enough" as I didn't want to spend ages figuring out the optimum way to organise pixel images.
And here's a copy of 8 wide blanks in case people are lazy and have the same idea.
Edit:
Further tile ideas because while I'm here why not:
More ash wasteland, dead and/or burned forests and charred landscapes, settlements that have been damaged or destroyed.
And well it is a fantasy tile set:
Fantasy landmarks, monoliths, giant statues, etc.
If it's possible with such a little amount of pixels to create very different settlements, then:
Non-human settlements, elven, orc, dwarf, goblin, etc.
(if not possible with this sizing of pixels, perhaps CuddlyClover would you want to make a larger more detailed tile set? Not sure how scaling would work, but I could potentially create bigger versions as a test and see if you/anyone wants to roll with it for those that want more detail)
Fantasy forests, i.e. different colours to green, different shapes, or perhaps just really big trees/a central giant tree.
As you said "x" flips the tile horizontally in tiled, could have a lite version of the tileset which just has 1 variant of each tile type, and a bigger set with multiple variants, preferably all alignend the same way, and then pointed out to use x to flip the tile horizontally.
Rather put ideas out there in case someone wants to do something with it related to this tileset