Instances of non-Jews hiding Jews were numerous. The Righteous Among the Nations is a list of people recognized by Yad Vashem, the Israeli Holocaust Museum, for having assisted Jews. But, it only counts people who helped Jews without any expectation of payment/reward, purely out of altruism (at least in theory, individual cases are difficult to evaluate, e.g. Schindler from Schindler's List). So a large number of non-Jews did help Jews.

But doing so was dangerous, and many non-Jews were just trying to get themselves and their families through unscathed. And a lot of Europeans at the time didn't really like Jews in the first place. A lot of non-Jews more-or-less ignored what was happening. Some of them thought whatever was happening to Jews was bad, but didn't really do anything about it. Some rationalized and condoned it. Smaller numbers either collaborated and helped the Nazis, or aided Jews in some way.

It's worth mentioning that there were antisemites who helped Jews, because even if they didn't like Jews they thought genocide was wrong. And there were people who weren't antisemites who didn't help because they either willfully disbelieved what was happening, or because they were afraid of the risks to them and their families, or for other reasons.