An amazing time, beating an almost 30 y/o record. It's about 5 meters faster than when I watched Charles Dobson of William and Mary win the IC4A's in 1974.
For fun, in the slo-mo head on, watch how good his technique is in how little space there is between his legs and the hurdles as he clears them. All of them do it, really, but Holloway's is a little special. He is still improving. BTW, you should know that when track results are delayed it is a good sign, because it means there is some sort of record and they want to make sure before announcing it, because it's embarrassing when you get something like that wrong. So after the first fifteen seconds Grant likely suspected something was up.
Records do belong somewhat to eras. Now that everyone knows to scour obscure school track meets and get kids signed up quick there aren't many who escape, and those usually don't compete because they are in other sports. The odds are LeBron James could have set the triple-jump record with only a year's training, for example, his only competition being other basketball players, a few of whom might have had more of a knack for it than him. Mike Conley's father was a world-class triple-jumper, and the 70s Denver Nuggets star David Thompson was as well.
Better shoes, better tracks, better techniques based on video and biomechanics, better training and medical care is a lot of it. I don't know if Jesse Owens would be a gold medalist if he competed in our era, but he wouldn't be embarrassing.