First off, get rid of that HDD and get a SSD, or at the minimum, use the HDD for data storage only and use the SSD for the boot drive. That'll give you the biggest quality of life improvement.
Second off, just upgrade everything, or at least the CPU/motherboard. Sure, your motherboard may support newer gen Ryzen processors, but BIOS updates are 100% required for that. If you want to just try upgrading your CPU, make sure to refer to the CPU support list for your motherboard. Even though AMD officially started supporting 5xxx series Ryzen processors on 1st gen motherboards about 6 months ago, it's up to your motherboard manufacturer if they want to push that support onto your specific motherboard. If your motherboard does happen to support newer processors, keep in mind that an older motherboard will never pull the full potential out of a processor newer than what it was designed for.