User blog:SolZen321/Why are Aliens Humanoid?

So in previous blogs, I looked at realistic reasons, or what a realistic version of alien invaders and giant monsters would have for attacking Earth/Cities. Yet another question has come to mind. Why are so Aliens many aliens...Humanoid?

Now to be clear, I know not every alien is humanoid, and I know the literal reason why so many aliens are humanoid in the Ultra Series. Also, this is a theory blog, so it's less me telling you and more me brainstorming realistic explanations.

Definition
Now before we start let us be clear on what I mean by 'humanoid'. I do not refer to simply the aliens that are Humann lookalikes. Star Wars has a better definition for that, 'Near-Humans'. When I say humanoid I refer to the actual shape of their anatomy. This includes beings like Alien Baltan, Alien Zeton, Alieh Mephilas, Alien Empera, even Temperor. All of them are species that bipedal, two pairs of arms, and a single head. The word Humanoid literally is refering to a being's overall 'shape' not exact appearance.

Evolution and Civilization
Now, as we sit and question and question the abundance of humanoid species in the Ultra Series, some more disparate from the human image, some closer to Near-Human and others inbetween, let us look at the perquisites for a species developing a civilization I won't go into length about environment, because my prior blog about invaders essentially explains a lot of that. Brain power, is a given, these are sentient species. So let us go with form. Scientists theorize that the humanoid shape is best conductive for producing civilization. It has arms, and usually digits capable manipulating objects. It upright posture means a creature can better survey the environment, and the combination of these two things means a species can probably better adapt to different environments on a planet. Especially important on a hostile world. That said, there are other aliens who do not have humanoid forms, but whose form still seem to fulfill these requirements. For example Alien Cool and Chibu, the two cephalopods from Ultraseven. Their levitation and seemingly natural telekinesis means they can easily manipulate objects to produce technology. Cool has claws, so even if he lacks mental powers, he is still able to conceivably move things.
 * 1) Brain Power: A brain with the mental ability to remember details, device plans, solve problems and communicate finer details.
 * 2) Form: A body capable of manipulating objects, tools, and devices in such a way as to produce tools for use. Basically a way to manipulate the world around you, and that is less glamorous than I'm making it sound. Your opposable thumb basically fulfills that function.
 * 3) An environment conductive to civilization: This is important, because even if a species has the first two, without the right environment to develop, they may just slip back into beasthood. It's why civilizations from Water Worlds are weird. How does one start a fire underwater?

The Royal Tree
So let's go back to this piece of lore that the series will probably never talk about again. So we (by 'we' I mean 'me) theorized that the reason for the seemingly invader filled universe of the Ultra Series is the fault of the Royal Tree of Kanon, producing too many civilizations in a universe where truly comfortable worlds for living on, were in comparison, sparse. Ergo, there was competition on living space in the universe, which was the most viable resource for a civilization advancing at any credible rate.

The theme of Reason versus Instinct has been part of the series since, Another Genesis, or maybe even longer, if you look at Tiga, Dyna and especially Cosmos. The blue calming light, versus the red aggresive light. Very commonly, the red light is attributed to monsters, and even invaders, but the blue light is associated with Ultras, mankind, and civilization. This theme also seems to appear with the War God, that protect the tree that spreads the light of civilization, represented by the blue glow of its fruit, versus Queen Bezelb and her brood, whose venom strips mental control from a victim reducing them to animals to be controlled by the hive and the queen, which is noted by a red glow.

Interestingly the guardian created by the tree, the War God, is humanoid, and the people of that planet, are akin to humans in terms of appearance. Grant Orb Origins hints that the human form is fairly common, and we have no idea if their people evolved on this world or migrated there, but the fact that the species that literally lives with the tree are humanoid, is something to note.

To get to the point, I'm putting forward the theory that the tree causes evolution to go in a certain way that induces a humanoid shape for a species.

But what do you guys think, what in-universe reason do you think explains why so many species are humanoid.