Both Uses of

inferior
in
Childhood's End

The objcctions and policies of these groups varied enormously: some took the religious viewpoint, while others were merely expressing a sense of inferiority.†
Chpt 3 *

inferiority = the state of being of low quality or of lower quality than something else

It might be-though this he refused to accept-that mankind could never be more than an inferior species, preserved in an out-of-the-way zoo with the Overlords as keepers.†
Chpt 22

inferior = (adjective) of low quality, or of lower quality or rank than something else OR (more rarely as a noun) a person of lower rank or status

Definitions:

(1) (inferior)
of low quality, or of lower quality or rank than something else -- sometimes used as a noun to refer to a person of lower rank or status
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Less commonly, specialized senses include:
- anatomy and botany -- a lower position on a body or plant (or pointed downward)
- typography -- a character that drops beneath a printing line (such as with subscript)
- astronomy -- having an orbit relative to the sun that is lower than earth's (making Mercury and Venus inferior planets)