the writers may not clever enough to realize this, this probably happened on complete accident
but Kevin is an ultimate contrast to Steve/Stevonnie
they share a color scheme to show that they are someway similar, and even>Steven + Connie = Stevonnie >Connie + Steven = Ceven = Kevin
kinda dumb there but why not
but Steven has the literal power to get into people's head, without their consent, but they become better for it and he's nice about it
Kevin gets into people's heads because they let him, and he fucks with them
Steven is nice to everyone, Kevin is a jerk because he thinks its funny
from what i interpret by the writers is that Kevin is basically that pickup artist that they wish they could have told off, i doubt there was any man like this in their life rather just a power fantasy for them to beat this kind of guy, in their view the worst kind of guy
Kevin is basically the worst aspects of masculinity to them, maybe just masculinity in general as Kevin doesn't really do anything that bad
however Steven's ultimate journey as a hero is to embrace the powers of femininity and to keep his innocence in an increasingly darkening world.
he doesn't really reject masculinity or become that different that many times in the show though (in a way Steven is a reversed roll of the coming of age hero, rather becoming a man he will become a woman)
Kevin is also the first antagonist to make Steven act differently, rather try to make friends with him he instead tries to fight him only to learn fighting him is a mistake
Kevin is Steven's rejection of masculinity, Kevin i's Steven's first real challenge in his hero's journey.
tl;dr Kevin is Steven Universe greatest villain