Imagine that honeybees had philosophers and ethicists. Would it make sense for a worker bee philosopher to start her examination of morality based on herself and herself alone? Her whole concept of survival is intrinsically dependent on the queen and on other workers; she also can't breed. Before even discussing her concept of ethics, all of her core values are inseparable from her position in her hive society.

I'm not even proposing moral relativism here, I'm saying that any human conception of morality is inextricably connected to humans as social creatures. Even a self-centered individual has to bear that in mind as well - if "building a legacy" is a valuable goal to some specific, fully selfish individual, it's important to note that there's no such thing as a legacy without other members of society to experience or remember it into the future.

Assumptions about philosophy that start and end with the individual consciousness are IMO not "more rational" but instead something inhuman. How can a fully isolated human even be considered the same kind of existence as someone in a collective?

This is an aspect of "natural law" and "social contract" discussions that I think gets buried when people start focusing on individual positive/negative rights. If you're the only conscious individual around, there is no value in a concept of "rights" to begin with - a "right" only even has meaning when it affects another conscious being. Conjuring up some idea of "rights" one has when fully isolated and then applying that as a foundation for rules in a group is nonsensical - a fully isolated human could never have the language to conceive of "rights" (or even language at all).

Accordingly, conceptualizing what, if any, natural rights exist necessarily must begin with people in a group, not in isolation. Putting a human in a vacuum and then considering how they would behave at that point in a thought experiment is creating a non-human and then trying to give it the same label.