TeemoBackup This will sound brutal, but you've got to roll with the punches (for now at least).
From my personal experience, Rainbow's Newcomers playlist is plagued with smurfs looking to "noob stomp". When I say "plagued", I'm talking 4/5 games. Should Valorant add a similar mode, I've got no doubts the same will happen but worse, since Valorant is free to play.
For now, playing against people who greatly outmatch you could be more beneficial than you realize; face them enough and you'll eventually learn to overcome and surpass them.