Throughout the galaxy there is a high incidence of (more or less) genetically compatible human species, especially amongst space-faring civilizations. While the cause of this is unknown, it is possible that the basic characteristics of humans are something of the lowest common denominator for sapient life. Though no single human species is universal, it is not unusual to find at least some evidence of some human species, or proto-human species, evolving on a planet, even if that species eventually died out.
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It can be surmised that for whatever reason, humans are a popular template among the Energy Beings, but obviously not necessarily the only template.
(ooc: This is to explain the existence of multiple human and near-human species and to allow for the incorporation of new material from outside sources without having to explain the presence/centrality of humans in that source.)
