No, humans output a stream of tokens that sound like what a being with subjective experiences would output. Both you and I make an assumption that this stream of words is at least somewhat representative of what the are experiencing and that the person is not a p-zombie.

But you have zero proof that their words aren't a confabulation, you can only know than when you output a similar set of words you had a subjective mind state they represent.

Even so you still cannot ever test for it.

The very best you can do is define human consciousness as requiring the functions of a human brain, and try to figure out (decide/agree) the chances that something which is working loosely on the same principles is or isn't conscious.

At the end of the day it will always be an agreement, never scientifically proven as fact.