Is human nature good or bad at its core?

At the core we are good to each other, which helps us thrive as a social species. There are bad actors who take advantage of that goodness, but it is the minority.

We are not good to other species. We've dominated our way to the top through the Extinction of several other creatures. However such is not an abnormality in nature and another species would be likely to do it to us if they could and stood to gain.