You are right, I don't plan animating these, but the workload is still a bit much and lowering the color count should make creating new sprites faster.
The reason why they use so many colors is because I use one big palette with around 100 colors, which I extend as needed. I created that palette by drawing different materials and figuring out which colors I need to give them all a high fidelity look, more akin to digital paintings than pixel art. I did that to get a consistent look for them.
I now have reduced that palette down to ~64 colors.
Afterwards I remapped the sprites, shaving off ~10 colors on each.
This isn't much difference yet, but should improve future sprites a little. I want to maintain a high fidelity style, but I will have to experiment a bit more to find a good middle-ground between detail and work load.