This is a really good and precise characterization of the pre-BoBW-Borg. Footage on nature shows, when sharks just seem to ignore all the tasty fish swimming about them, has raised my eyebrows, too.
I think it was also a writer's error in BoBW1 when Shelby says, "I thought they weren't interested in human life forms, only our technology." This remark over-interprets the events of Q Who?. In Q Who?, the Borg communicate with the crew, threatening punishment if they resist, and when they do resist, they punish the crew, by slicing out a chunk of the ship and taking away 18 crewmen. Clearly, the Borg know exactly what humans are, they know what humans' relationship with their technology is (in contrast, say with V'Ger, who is evidently clueless), and they have already demonstrated that they will communicate and deal directly with the crew, even to the point of taking some of them away, when they feel like it.