I think there is innate tribalism in all of us. We can all rationally fight it and we rationally know what is morally the right thing to do. But it is in our core psychology to look for similarities/differences and identify as close/distance to other people.
The Ukrainian government has also made an amazing job at galvanizing EU social media around this. The message is clear, it is us, your european brothers and sisters who are suffering right now, please help.
In many ways the Ukrainians have succeeded in an information war where the Georgians, Armenians, Sirians, Yemenis have been unfortunately less successful.