It is highly unlikely that spilled water on your keyboard will cause your images to be pixelated. Instead, spilled water is more likely to damage some of the components of your MBP (depending on what you did right after the spill and how long it has been since).
If your internal drive was damaged, you would have all kinds of problems reading from and writing to the drive, which means it would still not work the way it used to (according to your question).
As a test, I wanted to copy some of these images to a USB drive and try watching them on another computer just to see if they still look pixelated:
- If they do you know your data is corrupted.
- If they don't you know that you probably have another problem with your MBP (for example, graphics card damage, screen damage, etc.).
If you do not have access to another computer, email the pictures to your smartphone and view them on it.
As an additional step, it would be worth testing the hardware.
Testing the hardware
You do not specify the model for MacBook Pro, so it is not clear whether you need to use Apple Hardware Test or Apple Diagnostics to do this. If MacBook Pro was introduced: