Yes you’re right about having more time and better reflexes back then, but at the same time I feel like I pick up on cues and understand more what the developers intended for the player the older I’ve got. I remember playing the same levels over and over as a kid and eventually losing motivation to continue (this is somewhat balanced out by the fact that yes, I’d have more time, and also I didn’t have as many games - so I had more incentive to keep playing one to completion). Whereas nowadays I’ve got more patience and I can work out ‘oh I’m probably meant to go that way’ based on my experience of playing lots of different games over the years. I’ve built up more of an intuition for these things.
That said, I’m not sure I could beat many NES games!