Your images textures are way to little. They are under you render resolution. And the bad aliasing is already be in the image textures.
At least, they should have the same resolution as your render output. Bigger would be better in your case.
And you have to option to render at a higher resolution.
I’m sure, that you watch the render in a wrong resultion. You’ve the possibilitie in the Renderview to zoom with the mouse wheel. Maybe you’re not at 100%, above and under decrease tex readability very much.
Did you tried to save you’re image (F3), and looked then at it?
If thats not the case, check you Antialias settings in the render tab.
Get big images and scale down when texturing. Cause the computer to “throw information away,” not to “invent it” by interpolation.
(You can also have fun with texture-painting, taking several different texture sources and combining them artistically to create just the right texture image-map for your particular construction and camera-angles. But in all cases, the image-data needs to “be there,” in your original sources, in far more detail than you actually use.)