You're trying to swim against decades of gaming tropes, wherein a "level 5" character was always stronger, better, faster than a "level 4" character, and a "level 10" character could one-shot both of 'em dead.
In some respects perhaps, the XP in 7Days is almost even a little mis-named, if it's not something that is totally beneficial to the player, as it is in just about every other game ever made. In 7Days, it's a more nuanced , double-edged sword, but new players especially aren't going to have even the slightest idea of that.