I say that aliens that are basically built like earth animals like these 3 in this picture
yes species of animals that evolved on heart thousands or even millions of years before we humans ever appeared I mean when you stop and look at their body plans and the fact they are genetically similar to earth's species you gotta realized they left earth when it became too hostile for them and that they returned for recolonisation projects with us as Bio engineered swamp and Savannah apes in Africa and the human like gods and the Nordics like the titans, olymipians, jottun, asgardia a and others are space born reolder sibling races of humans that appeared hundreds of thousands; of years ago