[Humanism] refers to a doctrine of feeling spite toward humanity in general, judging that it deserves to suffer punishment. Ideally with no chance of redemption, as the sin is being human, rather than any particular act.
[Secular] refers to a doctrine of hating and fearing consciousness; trying to deny their own consciousness and getting you to doubt and disparage your own consciousness. Believing in no free will, saying you're nothing but meat, etc etc.
Everything else you've heard about secular humanism is cope or camouflage.
Anything humanist works the same way. Anything secular works the same way. Secular humanism is merely both together.