Image quality issues

[#1]

Why do my video look so bad? Not only the previsualisation, but also when I export the video, no matter the format (mp4, AVI, Quicktime...).

I made the images with Photoshop (RGM 8-bit Mode).

Thank you in advance for your help!

[#2]

Preview is set to 50% should be set to FIT.

Post screenshot export settings with left tab to output with an image and properties of the image.

 

[#3]