I'm confused by your first question, then, where you wanted to get RID of the lines. So, the question is really how to get a realistic siding material?
Too many possibilities to answer. An easy answer, without alpha bumps, is to paint a more realistic shadow line (soft shadow) in the texture image... it'll still look fake because it won't interact with the light properly.
I can't see the jaggies that your'e talking about, but if they are present, set method to best, antialiasing to best, click the Options button (still on the Effects tab), and check 'texture antialiasing' and slide the slider all the way to the right. If that looks OK, then try the slider at different positions to the left to speed things up.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB