The Overmind used its telepathic link to its Cerebrates to "save" their personalities within itself and restore them in newly-grown bodies. That's still just basic Hive Mind telepathy, nothing like what we've seen in the Psionic Ascension Path.Overlord was capable of using psi power to resurrect their cerebrate when the khala protoss tried to kill it. Hence the dark templar had to step in and do it for them despite the distrust between light and dark templar.
Every example of Zerg psionics you have drawn upon has either been not actually Zerg-related or just some variant on "they can send and recieve and rely upon telepathic signals", which is baseline Hive Mind capability in Stellaris and has no indication of being a higher-level psionic ability such as those shown in the Psionic Ascension Path.
Overlords gave Zerg spaceflight, not telepathy- telepathy was inherent with the creation of the Overmind to unify the Zerg.