A few remarks from me.

We don’t need to know about everything we don’t see.
It’s pretty irrelevant why the cage is there.
On the contrary when something remains in the dark, there is room for mystery and speculation.
Hitchcock was a master in this discipline, or do you want to know why the birds became aggressive and why they suddenly calmed down again? 😉
I do not believe that the alien is only keen on humans and has spared the cat, but that the cat could escape (see point 1 speculations).
If you integrate the Dallas death scene, there are continuity flaws to Cameron’s “Aliens”!
As a reminder: When the camera shots show the cocoons, Ripley tells Lieutenant Gorman that she’s never seen anything like this before!
I don’t know if you have the technical skills, but it would be nice if someone could finally remove Ripley’s nosebleed before the fight with Ash! Because the nosebleed results from a previously shoted scene that was never used and fell under the cutting table!
In contrast to the cage question of the cat, this scene makes no sense at all. Why does Ripley bleed out of her nose while talking to Ash?

Otherwise, I wish you a lot of interest in your work. 😃