Zeus is a complex character; although he is chief among gods, with many noble qualities, he is also deeply flawed. Among various sites on the internet 1 2 3 4, there's this passage which suggests that he is a compilation of various supreme gods:
Zeus was mighty, glorious, awesome and wise, although he did show a certain degree of surprising foolishness and naiveness when it came to hiding his love affairs. Some historians attribute this less than noble behavior of the "noblest one of all" to the fact that Zeus was most likely a compilation of many "supreme gods" from different areas. When his worship spread to an area which already worshipped another god, some of that god’s qualities as well as his wife or lover were transferred to Zeus. Aside from the endless affairs Zeus was different from other gods in that he did not participate in the arguments and the resulting petty scheming that made up the daily activities of other gods. Being this wise ruler, he also demanded just and righteous action from men. Zeus was however vengeful, as can be seen in The creation of man by Prometheus, but only rightly so.
Unfortunately, this passage is unsourced and those sites might all be plagiarising some unknown, original source.
Is this assertion true, was Zeus a compilation of other gods, combining their qualities? If so, do we know which gods became lumped into Zeus, and what were they like?