Yeah we can't literally know what cats are thinking, but humans do tend to anthropomorphise so we can't really help attributing our observations of their behaviour into what we believe they are thinking. Very egotistical of us.

My observation they think we are a bit useless comes from the 'gifts' behaviour of bringing things into the house. My cat brings in small lizards- thanks buddy! Could be any number of reasons they do it, but I find it amusing to ponder if he thinks I'm not good at hunting, so he better take care of this important cat business.