People are evolutionarily hard-wired to pay more attention to threats than to non-threats, and more to greater threats than to lesser. If aliens in a story or movie were less intelligent than we are, they would feel like less of a threat; if they were non-hostile, they might feel like no threat at all (as in “E.T.”, which is therefore a children’s movie). so stories about them wouldn’t interest us very much and wouldn’t be profitable.
There are SF stories revolving around interesting variations on these themes. in one, extraterrestrials arrive whose intelligence has the same standard deviation as ours, but a lower mean (about 95)—they have a species history hundreds of times longer than ours, so they have had more geniuses (by our standards), just spaced out quite a bit. They strike us as a little “slow”, and, when we get over out idea that they must be smarter (but tricking us for some reason), we scam them left and right.
In another, completely benevolent extraterrestrials much smarter than us arrive, and, despite the best of intentions, make us feel so stupid that we go into a species-wide funk and die off.