>>1121268921)This is a half-ass method of doing so
Instead of having this be discussed in the show itself, going the Word of God approach is much lazier taking multiple magnitudes less effort.
2) It's never even implied in the show that Earth is the first planet with intelligent life Homeworld has come across
If Earth had such a novelty it would have been mentioned at least once by somebody. We see evidence that contradicts this notion. Even though Steven got their attention by speaking to them, they try to kill him. To me, this shows that Homeworld did have a policy on intelligent life, and it was killing them on sight.
3)Even if Earth was the first planet with intelligent life it makes Homeworld's act even more suspect
You'd think that if your empire has existed for 10s of thousands of years if this is the first time you've encountered other intelligent life there would be some more reverence in how that life would be treated. Based on the story's time frame, they would have found earth during the Bronze Age. If they scouted the planet they would have found human settlements including the pyramids and other stone structures that were built at that time. This would have been a new experience for Homeworld, yet Earth is treated like nothing special. Just another planet to be harvested the local life be dammed.
4) If this is the case then why does Homeworld have such an expansive well-armed army?
This can be explained by them wanting to keep their colonies in line. Yet due to the nature of Gems and Homeworld society. This wouldn't justify so many troops. Mostly they have little to worry about yet they are pumping out troops and laser cannons like they are expecting a fight.