The Common category includes the following blocks: Paragraph, image, headings, list, gallery, quote, audio, cover, video. The paragraph block is the default block type.  It should not have any alignment of any kind. It should just flow like you would normally expect. Nothing fancy.

This is a test for Jetpack’s Tiled Gallery. Install Jetpack to test. This is some text after the Tiled Gallery just to make sure that everything spaces nicely.