I encountered many like him in other Creative maps like Castle wars and Prison breakout. After that he just hid somewhere out of sight, not fighting anyone, until I was alone somewhere, then he'd come and fight, then ran away and hid again. The sixth time there was another player near me, suddenly his shots were like a default noobish player, he couldn't decide who to shoot and didn't hit anyone when he did shoot. I fought him 1v1 with shotguns like 5 times, he hit every shot every time, even though I moved rapidly, and all of them were headshots. He had something like 150-5 eliminations/eliminated ratio when I joined that game. Just the other day I encountered a cheater in the Creative map '50v50'. I think I am an above average player, I win about 90% of 1v1 duels, so I notice when something is not right with the aiming of the other player.

In which they cheat and kill unskilled players for sport, just to get their kill ratio up.

It's much worse in Creative competitive-like games. I'd say I've encountered a cheater in about 3 of every 10 games, that I know of of course. I've noticed cheating getting worse and worse over the the years. I've played this game ever since Chapter 1 S3.

The people in Reddit who 'firmly' deny that there's cheating in Fortnite are probably cheaters themselves, cheat sellers, or just Epic fanboys.