Are you saying that if we had no capacity for shame, we wouldn't think sex or anything else is "low-minded" or vulgar? That there would be no distinction between low- and high-mindedness?

Perhaps that's so, but how long do you think we'd survive as a species with such a lack of judgment? We do judge our species to be "higher" than insects, regardless of the virtue signals we may wish to send out. So what we have in common with insects must be among the most primitive aspects of ourselves.