Wanna play a little devil's advocate here.
Are you sure you can identify an insect or you just assume (or your brain makes the match) of it as an insect because it is the most probable/desirable object of those characteristics in that scenario? I mean if I were to throw a paint ball or any other similar sized object out of context, would you be able to identify it as such or just assume that another bug spashed in your wind shield?
My point is that a pilot climbing and seein such object for a small time and having his mind in so many other things would much likely to just default to "drone" and raise the concern, than actually try to figure out what exactly is
Not saying it is right or wrong, but sounds like a probable scenario
I suspect that both can happen. However, you must have seen small items on the roadway that were unexpected, but you still identified them just fine. And that's without the benefit of changing parallax relative to the background, which makes any object much clearer. I can also say that I've easily seen and identified birds on takeoff and landing. I'm actually rather surprised with all the real life experience that everyone has of seeing small objects from moving vehicles that there is any doubt at all that this is perfectly possible.