Hi Palermo.
I'm writing as a noisy upstairs neighbor. My wife and I live with our 3 year old daughter in a wood frame coop that is notorious for noise. We can hear our downstairs neighbor on the phone pretty clearly, for example.
So we are very sympathetic to the noise our daughter makes. We have carpets everywhere with 1/4" sound absorbed padding underneath. This doesn't seem to help much. We bought her a bunch of thick, play cushion/mat things (they look like gymnastic mats, but about 5" deep) and she knows if she does any physical playing, she has to be on those. It's still not enough.
Kids this age very much need a lot of physical activity, and they will get it by hook or crook. You can't simply tell them not to jump or make noise. Their bodies will just find some way of moving. In normal times, we spend a lot more time out of the house getting that activity. But winter in a pandemic has been awful. No play spaces, no field trips, no zoo. The only thing we can do is go outside to the park. And if the weather is bad we can only stay out so long, or sometimes can't go out at all. She is recently back in in-person pre-school, so I hope that has been helpful for our downstairs neighbor, who I know is unhappy with us. Hopefully, as the weather warms up and the pandemic comes under control, we will be outside more.
But there's really not much else we can do.
So, what I would say is try to keep communication open and genial. Our neighbor refused to do this, and it made matters worse. We tried to find out a little more about their schedule, to help us manager our daughter's time in a way that might synch better. But they refused to do this and would only communicate with us through the super.
You should also consider that it's not that they don't understand how much noise their child can make or that they aren't trying to address it. But maybe they're just out of ideas.