Why am I being placed with level 50's-100's when i'm level 500

SBMM bro. Quite literally matches newbies / casuals / low skill players with more experienced players to net them easy wins. 

The reason it does that, is because if you feed those people easy wins, they're going to associate Apex with a good time (despite not doing anything), which makes them more likely to spend money on the game. 

Supposedly improvements are coming, but this is EA we're talking about. Money always comes first.