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These splash screens have been made to visually match my Clearlooks Gimp 2.10 Color Hinted Themes.
If you don't mind them saying Gimp 2.10, they should work with any version of Gimp capable of handling custom splash screens, but they should probably be placed to a different folder in your hard disk.
Here's what the official docs say for Gimp 2.10:
There are BLUE, ORANGE, PINK, RED and TEAL images in the pack, with Unframed (1) and Framed (2) variants (framed ones are also inverted aesthetically). This makes a total of 10 splash images. They are all in Full HD dimensions (1920x1080). Feel free to downsize them if they are too big for your monitor.
The splash images come packed in a zip-file. Unpack it and copy the included "splashes/" folder, into Gimp's Configuration folder. Feel free to delete any images you do not want (the rest will be picked randomly every time you start Gimp).
If you are having trouble locating Gimp's Configuration folder on your system, see the included Readme.txt file for detailed instructions.