So the Alien seems OK with animals

Not enough nutrients in a cat....Not enough of a meal?

Sense of smell must be incredible? determining  Ripley was carrying a queen.

I really don't know why a xeno attacks anything...can they smell fear pheromones?

If the hero stood still or stayed 'frosty' would the xeno ingnore them?

I think its safe to assume.... the Xenomorph has TWO Objectives.

WHAT can it use to Procreate....

WHAT would pose a Threat to its Existence and ability to Procreate.

So Jonesy would be seen as NOT a threat, but then maybe a Viable Means to Procreate.

Regarding FOOD, i would assume if the Xenomorph requires such things (indicated in drafts/novels) then it would not PASS UP a Jonesy Snack!

At that point of the movie, the Xeno's objective seemed to be getting to safety. Jones was clearly not a threat. Perhaps the xeno just observed J as a curiosity. Maybe it was as simple as that- but I wonder if it was some kind of acknowledgement that it recognized another living creature but was not related to its target- humans. Perhaps the xeno displayed a form of ethics.

Big Chap knew that the only thing keeping it safe from a smackdown was the box that held Jonesy back XD