Half the population is erased and then ultimately resurrected 5 years later. After the 'reverse snap' is the resurrected population now 5 years older or were they restored to the same age they were at the time of the snap, essentially jumping forward 5 years in time?
No, they did not age!
Q: What about those people who got dusted? What did those five years mean to them? Why didn't they grow older when undusted?
A: Yes, those people whom was lucky to survive the snap are 5 years older than the people who just got back. The reason Spider Man saw his friend again in high school at the end was simply because his friends was unfortunately also dusted like Spider Man was. Of course, there are people in his grade whom didn't die and they are probably already in colleges by now. To those dusted people, they had no conscious in these past 5 years. They didn't know what happened. It's as if they had just woke up from a long sleep. The only one who was aware about how many years has passed was Doctor Strange, because he has already seen that when he was time mediating on Titan. Parker's reunion with Ned was a touching moment. There are also people whom indeed moved on but suddenly was reunited with their lost ones. Yeah it's kind a complicated world now.