There is no defined census for the population of Humanity abroad in the galaxy, but based on meta-analysis of various corporate and system-level studies that compiled specific planetary censuses and the Hawkingnet Catalogue of Inhabited Worlds which recieves contributions from the Galactic Council and most colonial corporations, experts involved in meta-meta-analysis of the galactic population place estimates for humanity at somewhere between 30 and 40 trillion. This is, of course, an absurdly large number of people to all be considered a single "civilization", but for purposes of definition they do all share a root language and recognize the same groups of authority, so they do technically constitute a galactic civilization.
To suggest that a group that large all follow the exact same moral code, or fall under the same set of cultural touchstones, or even share the same values, is however ludicrous. The galaxy is a very diverse place, and in the following sections we'll try and describe some small aspects of it.