It’s not always perfect. Many factors could have made the system think you are a better player. Changing metas, hero nerfs and buffs, queuing with a friend who is better than you, thus winning you more games, etc.
The highest % there is gold. I’ve gotten placed lower and way higher than that
Your first games after your first placements, you also get more and lose more sr per win/loss to quickly find where you should be. Its possible you got on a losing streak to start your first season and crashed hard