Since Apple ditched the USB A port, you now have to use an external adapter to bring back the USB A port. USB A port is really essential port if you want to connect a flash drive, lightning cables to transfer data on iOS devices, connect a printer, mouse, keyboard and etc. We never know when these types of circumstances may arrive so it is better to back up this USB C to USB 3.0 adapter which is only $8 today, usually $10.
From the Product Page:
[USB 3.0 Superspeed] Up to 5Gbps data transfer speed
[Match Macbook] Unibody aluminum casing. 3 colors to match Apple Macbook
[Durable Aluminum Body] High-quality components ensure longer life span
[Tip 1] Need to push the adapter to the end till you hear a click
[Tip 2] Works with the original Apple Cable