This is another one of those things that I would argue is a continuum, not a binary dichotomy. I think it's totally reasonable to posit that human intelligence is not "fully general". But I would have a hard time with suggesting that we don't possess a certain measure of "generality" in our intelligence. I mean, humans have dealt with new situations before and apparently thrived despite that. Imagine the first human to live in an environment near an active volcano and who witnessed a volcanic eruption. Or just think in terms of new technological innovations - our intelligence is "general enough" to learn to use telephones, drive cars, do abstract math, etc. All things that the stereotypical "caveman proto-human" did not have to deal with and which would have been new to somebody at some point.