I think the precursors might've viewed humanity as a bunch of animals (cough, cough, ignoring Uprising, cough, cough). We don't have a hive mind and they might've identified intelligence in species based on many traits, but primarily, a hive mind. Like how we also have flawed definitions of intelligence due to our own biases.
I also think this is a fun parallel to us. We will build cities and ruin habitats, and while we may feel bad for it, at the end of the day, the general consensus is that our quality of life matters more than the lives of animals.
We might be able to look at birds, dolphins, and other intelligent species and go "Yeah, they're smart. But they're not as smart as us, they're still just animals. At the end of the day, they're less sapient (this means capable of thinking, while sentient means capable of feeling) than us. "
Corvids are incredibly intelligent, and are capable of making second level tools, but they're just birds at the end of the day.
I think the precursors might've thought of humanity like that. Do some research and come back with the report of: "Yeah, these are some incredibly complex pack animals that show a high degree of intelligence, capable of making second or third degree tools. Different regions produce different phenotype and they seem to be able to communicate in a rudimentary sense through a series of whistles, clicks, and other similar sounds. Though, they seem to lack a complex telepathy system, hive, or puesdo-hive, or lack one at all."
And everyone was like: "Oh, that's cool!" and then proceeded to go look at the atmosphere and land mass and be like "oh, that's a lot of land with a pretty good atmosphere, we could work with this". And not realize that we're thinking, feeling beings.
(I'm actually thinking of writing a fic with this concept, where it all comes to a head when Newt drifts with the Kajui brain and the Precursors are all freaking out because they're been murdering a bunch of, like, PEOPLE, and not just animals and Newt's just like: "Well, yeah, of course we're people! Wtf???" Would people be interested in that?)