Note for the future - if you're going to attach multiple files, like a game project, it's best to put it in a .zip file so there's only one file to download. I will take a look at the assets.
You only need power of two textures if you want mipmaps. mipmaps are only good if you're planning to zoom in
and out on your images.
I made a small demo of your survivor guy being rotated and scaled with different combinations of ALLEGRO_MIN_LINEAR, ALLEGRO_MAG_LINEAR, and ALLEGRO_MIPMAP. Mipmapping didn't seem to help at all, and resulted in a faded image when scaling down. Mipmapping doesn't do anything when scaling up. Shrinking with ALLEGRO_MIN_LINEAR and growing with ALLEGRO_MAG_LINEAR really helped though, when not drawing at actual size.
Here's the demo - MinMag.zip.
For some reason, mipmapping made the images fade when drawn at less than actual size.
Rotate around the center with the mouse. Mouse wheel changes zoom.