The version you flashed was before twrp had been found and is from September 2020. There has been many stable and weekly branch versions since but you need to install twrp first.
I cannot remember what branch the fastboot version was based on but as it is so old, it would be best to format anyway if you want to change branches to weekly or stable. But once you choose a branch, weekly ( nearly every week but may have small bugs) or stable (only updated now and again but more stable) you must stay on that branch. If you do, each update only requires a simple cache and dalvik wipe, no loss of data. If you decide to switch branches, then you must format your data due to possible partition differences between them. If you don't, you may get caught in a boot loop until you do.
So your next step is to replace your stock recovery with twrp using the phone in fastboot and connected to a pc. Once done, you can do all your updates from your phone using the twrp recovery. Just download your new branch version and install but as I said, as you are so far behind, might be worth formatting and restore your data after.
If you want some help and information on how to do this please download my guide from my mega page here,
https://mega.nz/file/fIoWUD4a#q1S3wYoOltgaPcchAiXc3dHal7Sf31k5BZQBM4xy6NE
Or of course, come back here and ask away. Everyone here are here to help.