It lifted my country as well as dozens of others out of developing world status. There's a huge delta in national wealth between post soviet nations who joined the EU and those that didn't for example. A rising tide raises all boats.
Your reply sounds like a cheerleader chant. :D
Did the common person benefit from this "lift" that you mention or merely the technocrat who was willing to do the bidding of the new master?
Yes, it lifted everyone. Take a look into any stat on minimum/median salary, standard of living, HDI in any Central or Eastern European country that joined the EU against those that didn't - the gulf is massive. Also having lived in one such country before and after joining - yes, the EU helped lift everyone upwards.
The demographic crisis is real in the Eastern European countries not in the EU (Western Balkans, former USSR) too, but at least the standard of living has massively improved in the EU member states.