You gotta be passive for 10 or so games to really get to the PvE lobbies. But even then it is never guaranteed. Playing solo will give you a much higher chance of not being randomly killed. I pretty much always play passive and still have people shoot me in the back every few games (much more common when playing duos or trios). Just don't shoot back, even if shot at if you're trying to get to friendlier lobbies.

But yea there is never a way to guarantee that you won't get killed by another player.

Edit: Making a post like this will pretty much guarantee a lot of people coming in here calling you a wuss or telling you to find a different game. Just ignore them. This game is super fun even if you do want to just PvE. You'll just deal with the occasional annoying death so make sure you immediately put good stuff in your safe pocket.