I’m semi-new to valorant and I’ve unlocked most of the agents except killjoy cypher astra and harbor. Should I unlock these agents because I think they aren’t very good and I would rather unlock agent skins?

Title, I've just started playing again, currently at a 30% win rate, I do relatively well but end up losing my matches. This is making it quite hard for me to rank up - why am I not vsing Diamond players? It's confusing me as it keeps s...