The importance of Lens

I've recently bought a BMPCC4K and a Lumix 12-35 F2.8 II after seeing a lot of good reviews on it. Now that I have bought it, I've realized that everyone else for cinematic projects uses the sigma 18-35. I feel like an idiot because I feel like I've bought the wrong lens after hours and hours of research, and now it will cost me more to sell my used Lumix to acquire an Sigma with an adapter. Is lens that important? Or can I still shoot good cinematic projects with the lumix?