If your HDDS are of the spinning type, then the bottleneck in their speed are the HDDs themselves. At best you can get write/read speeds of 200MB/s. By comparison, your Macbook ports has the capacity to support transfer speeds up to 10GB/s, when you're using is as a USB-C ports only, where, if you're using Thunderbolt 3 capable drives, they can transfer up to 40GB/s. Changing cables, usb-c connectors/hubs etc would make no difference.
If you like to improve the speed of your drives, you need to consider buying a new hard drive of SSD type. The cheaper models have a read/write speed of 512Mb/s, where the more expensive one's have transfer speeds up to 2Gb/s. Depending your needs/wallet etc, you may settle for something inbetween. Any SSD drive from a reputable company would do the job for you, just make sure you're happy with their speed and capacity. I'm using a Crucial X8 that has transfer speeds of 1Gb/S and I'm pretty happy with it. Other reputable drives, in no particular order, are the Sandisk Extreme/Extreme Pro, Seagate Barracuda, WD My Passport SSD and Samsung T7.