If you treat this logic seriously then dragons, griffins, sphynxes,
fairies, and winged horses are all also insects.
Personally, I feel like being an insect is less dependent on the
amount of limbs and more the taxonomical linearity of a particular
group of invertebrates, and fantasy creatures don't fit earthly
taxonomy by nature of being Weird Things we Collectively Made Up.
Erm insects must have a pair of antennae and a thorax. They also
have to have an exoskeleton. (Being an invertebrate, which a
centaur is not.) A centaur can't be an insect because it doesn't
have these features. A centaur is also based on a combination of
two mammalian creatures, and an insect is not a mammal.
with that logic a centaur with the upper body of an insect is a
spider since you net gain 2 (idk what the base would remove but it
would be funny if it only got rid of 2 legs each time, like imagine
a centipede?)
Back starting fresh after not playing for over 5 years, should be
fun to get "addicted" to this game again