Depends on what you’re doing and what your WiFi is capable of. WiFi will never equate to cabled performance, but in a case like yours it may not matter. Do a speedtest with each scenario and see the difference - Unless you are doing online gaming, in which case stay cabled.
Get yourself an Ethernet cable tester as a first step - Then see if you have continuity through any of the cables and mark them accordingly. Then get a simple 5 or 8 port switch to distribute the Internet. If your router has open ports you may not even need a switch.
This may be correct in a few years time when all devices have been upgraded to 6G, WiFi 6 spec or better … Until then I’ll stick to CAT6 or better!
There is no problem with doing that in principle, as long as the cable is protected and the run is less than about 100m.