Do you think they are plants? Fungi? Very large bacteria?
I am using one of the definitions of the word ''animal'' from Cambridge dictionary which is ''something that lives and moves but is not a human'', only in this case I substitute the word human for ALL intelligent species of Faerun, dragons included.
There is a definition of the word ''animal'' that includes humans too, since humans are technically animals, but if I were to use that definition my point wouldn't make any sense, and typically when we use the word animal we don't mean humans.
It's basic biology.
Indeed, but in the contest of this dialogue "animal" is not used in its biological meaning but in his common sense meaning, and in common sense there are "insects" (that include everything from centipoda and arachnida to proper insects), plants (in wich fungi falls), microorganisms (a group that includes all that is not visible by the human eye), and humans (that is the one animal species that has, scientifically proven, self coscience, astract thinking, ability in complex mathematical calculus, etc etc.. ).
This common sense applied to Faerun means to change "humans" with "all entities able of the same characteristics that humans have: being self constious, being sentient, being able of abstract thinking, etc etc.. ..".