There's A Reason So Many Aliens Look Human In The MCU

Guardians of the Galaxy Vol. 3 further highlights just how many alien species in the MCU resemble humans. Despite the various planets and locales, the vast majority of aliens are bipedal species with much of the same external anatomy as humans from Earth. However, there may be an in-universe reason for these similarities (beyond the more obvious real-world explanation).

Following the first two Thor films and the alien invasion in the first Avengers, the MCU began exploring the greater reaches of space with 2014's Guardians of the Galaxy, featuring planets/locations such as Xandar and Knowhere. As seen in the multiple Marvel space movies that followed, most aliens in the MCU look like humans with similar structures, the most major changes often being skin color, hair, eyes, and differences in limbs. Following Guardians of the Galaxy Vol. 3 where even the High Evolutionary's perfect society saw animals being rapidly evolved to be bipedal with more human-like features, there may be a reason for the resemblances.

Many MCU Alien Species Can Appear Human

Human-looking aliens are everywhere in the MCU. The first to be introduced was the Asgardians. Apart from being stronger with longer life spans, powers, and advanced technology resembling magic, there isn't really anything that externally distinguishes the Asgardians from humans, and they virtually look the same. The same is true of Xandarians as seen in Guardians of the Galaxy, home of the Nova Corps and their central headquarters. Both versions of the Kree look human as well. Just like in the comics, the main difference between humans and the Kree is that some Kree have blue skin while pink-skinned Kree (like Jude Law's Yon-Rogg) look just like humans from Earth.

Beyond the High Evolutionary's creations, it's worth noting that almost every alien seen on Knowhere and OrgoCorp in Guardians of the Galaxy Vol. 3 is also bipedal and human-looking. Some have different colors of skin not found on Earth like yellow or blue (or green in Gamora's case). However, the main differences are typically found with the head as some background aliens are featured having more exotic hairstyles and eyes while others may have other features instead of hair. However, one would think that more of a variety of shapes and sizes would be found, especially with Knowhere being compromised of aliens from all over the galaxy.

The Celestials Created Many Alien Species In The Same Image

In the original Marvel Comics, it was the cosmic Celestials who were responsible for so many different alien species looking human, seeing as how they were the ones who created them all in their planetary experimentations (including humanity itself). Essentially, this means that several different species were all created in the same basic image, with only minor alterations occurring either through additional Celestial experimentation or the various processes of evolutionary adaptation with differing results from planet to planet. It stands to reason the same is likely true for the MCU as well.

Ultimately, the idea that so many species are bipedal like humans in the MCU because of the Celestials makes sense. In 2021's Eternals, it was established that the Celestials were very much like their comic book counterparts in that they were responsible for the Big Bang as well as the constant creation of new planets and life forms. This confirms that they created more beings beyond those living on Earth. Even the synthetic lifeforms they created known as the Eternals resemble humans, further proving that multiple species were created using the same basic image and framework (including humans).

Overall, it's a solid in-universe explanation for why there isn't more anatomical variety in the MCU. While there are still aliens that are bigger with more drastic changes in their physiology, the majority resemble humans. As such, it tracks that it's thanks to the Celestials and the major hand they played in the creation of life itself in the MCU at large.

Aliens Looking Human Has Real-World Reasoning

While there's a "canon" reason within the MCU, it was obviously established for real-world reasons and practicality. It's simply easier for Marvel Studios to have most aliens look like humans on a production level. Rather than spending the dollars to create multiple CGI aliens of all shapes and sizes, it's far cheaper to use make-up and prosthetics on a real actor for live-action projects such as Guardians of the Galaxy Vol. 3 and similar MCU projects. Likewise, humanoids are more naturally more relatable, and it's arguably more challenging to write stories if most of the characters looked bizarre.