Please help me understand why people say "I am a human being" [angry question]?

I’m really sorry for sounding so mad. My online posts usually sound mad (when I’m not) but right now, I am actually mad.

There are MANY thing in life that make no sense to me, this is one of them:

When people say “Well I’m only human” or ”..I am a human being..”
WELL… WHAT THE **** did you think we thought you were?
We (humans) are the only ones who can SPEAK. afaik
So the fact that people say it, makes no sense to me.
Is it just an excuse for Failing?

tnx
I am not mad now