Honestly, Hao Ren was not surprised by the First Born's space combat capabilities.
This powerful primitive creature had already demonstrated a small part of its fighting ability. It could control gravity, produce shields, distort space, and know how to use anti-air firepower to destroy targets in the face of meteorite attacks. All signs indicated that the First Born knew what space was all about from the very beginning—at least it knew what 'air combat' was. Plus it had destroyed the lunar city of the Ancient Magic Empire. So of course this monster could take the war to space.
Only that Hao Ren did not expect that the 'space ship' it created could be so smart.