The point is that the people who did witness the crucifixion , or knew it to have happend, would in general be unlikely to believe in the resurrection, because Jesus didn't physically appear to most of them. Hence why Christianity didn't 'spread like wildfire' among the Jews in Palestine.
Except that there is a claim that the resurrected Jesus appeared to 500 of them in one place. If you had been a witness to such an astonishing thing do you think you'd just mosey on home and mutter about the price of fish to your family and friends.
Of course not, you'd be telling everyone you knew (perhaps including plenty who might have witnessed the crucifixion or other purported 'miracles'). And they'd tell the people they know too. This news would have spread like wildfire. And given that elsewhere there are claims that thousands had been witnesses to other miracles, who surely would be highly receptive as they'd seen miracles too.
Given that the population of Judea was only about 100,000 you'd end up with a pretty sizeable proportion of that population as either first hand or second/third hand witnesses to claimed astonishing miracles.
Really weird that by and large they did not believe in the christian claims, did not follow Jesus, rejected the developing religion.
Almost as if there were no witnesses to the claimed events ... perhaps because they never happened as claims decades later by unknown writers, writing in far off places and in a different language from that spoken by the people around at the actual time and in the actual place where the events were claimed to have occurred.