Unity has 59% of all games Godot has 19% Gamemaker has 5% And unreal has a bit below 5%
Compared to last year Unity (-4%) Godot (+7%) Gamemaker (-6%) Unreal (~)
The gamejam was only 48 hours. Not enough time to compile an Unreal starter project. /s
But seriously, your iteration times will not be fast enough for a jam if using C++. You could use blueprints, but what programmer would want to actually do that? And then you will probably have issues with the web export, which grants you a huge visibility boost. Unreal is probably one of the worst engines you could use for a 48h jam.