Should morons be forgiven?

Is being stupid a mitigating circumstance before moral judgement?
Or is it a moral imperative to avoid stupidity.
And if we are guilty of stupidity, aren’t we morally obligated to do something about that.
Lots of critters have brains.
Only humans have a mind.
If we do not develop our minds, we are stupid, and really no better than a cow or a dog. Who have brains, but no mind.
So what is the excuse for stupidity?