Yes he was human, but no, that does not mean we need to feel we are able to relate to him.
Different humans are on different levels, sometimes worlds apart. The people from tanach
(including David) were on a completely different level than we are on today.
“Anybody that says David sinned is mistaken” is a quote from chazal. It means that what we think were David’s sins are not really what they were at all.
Do I understand that?
No. But that’s the point.
I realize this doesn’t answer you’re question, but I am questioning your need to be able to “relate” to the people in Tanach.