Miyn-Skruwians are very different from Humans in biology, psychology, and language, but not so different that coexistence is impossible.
Miyn-Skruwians are very different in biology and communication, but still have some basic elements shared with humanity, such as a comprehensible grammar system and concepts for life, death and an afterlife, and a system of morality and ethics comparable to some human beliefs.
The Miyn-Skruwian home world has almost nothing in common with Earth.
The sheer size of the universe means that there are sentient beings out there with varying biologies, no matter how weird-looking.
The Miyn-Skruwians have a completely inhuman appearance... but talk in Midwestern American accents and enjoy baseball and apple pie.
The Miyn-Skruwians are entirely different to humans in biology, language and living habitat... but their language is subtitled and reveals them to have the exact same fears about meeting humans as humans do about meeting them.
Invoked: The Precursors isolated entire worlds from each other and gave them completely different environments as a project on evolution.
Exploited: General Ripper successfully uses the alien appearance of the Miyn-Skruwian to argue that they can't be trusted not to try and conquer Earth.
Defied: The Benevolent Precursors seeded all intelligent life with certain basic commonalities to ensure galactic peace and diplomacy.
Conversed: "Now that is how you show alien evolution."
The Miyn-Skruwians fail to recognize humanity as sentient, or their Blue and Orange Morality causes a diplomatic incident of horrific scale, resulting in interstellar war.
The Miyn-Skruwians, have lived on a planet which has many predators on it and thus developed instincts which are comparable to human ones, even if their state of being is entirely different to how humans turned out. Because of this, they recognise humans as having something similar to them, and aim to learn more because they sympathize with how humans developed.
Reconstructed: Humanity and the Miyn-Skruwians are Genre Savvy enough to realize they don't know enough about each other to communicate meaningfully. But since they occupy completely different types of worlds, they simply stay out of each other's way.