If the Star Wars Galaxy is so vast, why are the majority of the species human (or at least humanoid) English speaking beings?
According to the Wookieepedia page about humans in Star Wars:
Humans were one of the most successful colonial species, having migrated and adapted to dominate a variety of worlds. [...] By the time of the Galactic Civil War, humans were the most populous of the galaxy's intelligent species, and could be encountered nearly anywhere communities of people gathered.
Although humans tended to regard their great adaptiveness as a skill, aliens sometimes reproached them for spreading all across the galaxy, forcing themselves upon ecosystems they did not belong to. Burta, a Krish female, notably held that point of view, which she vehemently defended against Jyn Erso.
"Some people would consider this a skill. Humans adapt. Got mountains? Build ridgecrawlers. Too much water? Build scub-subs. An ice planet? Use radiated igurts. People adapt."
"Yes, but should they? Either humans adapt, or they force the planet to adapt to them. This is not normal."
The latter were once humans that evolved into a different direction from the normal humans with minor changes such as skin color, eye color. Those differences in evolution depend mainly on external factors such as the environment of the planets that were colonized.
What's more, these Near-Humans are still genetically close enough to produce an offspring with a normal human.
Humanoids on the other hand, are simply alien beings that are not in any way related to Humans and only meet a few criteria:
- A head on top of the body
- 2 legs
- 2 arms
As for the English language, it is called the Galactic Basic in the Star Wars universe and it was created by the Republic as a language to be used by most of the species across the galaxy to facilitate trades and politics.
So it's no surprise for the humans and most of the humanoid species to speak it.