I’ve been kind of visualizing the overseer as something of a rudimentary intermediary between the life form and the crew, with a bit of the original invading code still buried somewhere inside it, if that helps at all. :)
The overseer was meant, originally, to be an interface between the ship’s human-constructed systems and the alien jump drive systems (much like the cartographer is the intermediary between the human navigation computer and the jump drives), but it has since evolved beyond that.
It’s no matter. We can assume the overseer was much more than was assumed by the human engineers.