*I use the term ‘alien’ very lightly. Usually they look and act exactly human, even though they’re from other planets that Earth presumably has not made contact with.
Par for the course for early SFTV, and even a lot of early prose science fiction despite the lack of budget limitations. I just finished watching the complete Rocky Jones, Space Ranger on YouTube. It was actually a fairly high-budget show for 1950s TV, shot on film with impressive special effects for the day, and mostly consisting of 3-part story arcs that were then compiled and released theatrically (the source of the Mystery Science Theater 3000 movies Manhunt in Space and Crash of Moons). But its aliens, who lived on other planets and moons of the Solar System and beyond (most of them imaginary), were invariably just humans in exotic clothes. In the early episodes, they did a good job having the aliens speak alien languages except for those who'd learned English from previous space explorers, and the storyline that Crash of Moons was a sequel to had an interesting take on computer translation to carry on a conversation. But later in the series, they abandoned that without explanation and had all aliens, even newly contacted ones, speak English.