How to transfer data from old MacBook Air to new MacBook Air

The easiest way to do it is wirelessly. It may not be the fastest, but it's the easiest and cheapest since you don't have to bother finding cables and adapters.

All Macs since just about forever have had Migration Assistant, and certainly any Mac running Catalina will. It's in the Utilities folder. Go > Utilities from the Finder.

Transfer to a new Mac with Migration Assistant - Apple Support

If you have been using Time Machine to backup your MBA, you can use that to transfer your files. If you have not been backing up with TM, why not start now? Create a backup on an external drive and then, after you've transferred your files, continue to use it as a backup drive on the new computer.

Back up your Mac with Time Machine - Apple Support

Yes, your new Mac will have USB-C peripheral ports, but a simple USB-A to USB-C adapter can be used to connect USB-A devices. They're inexpensive, about 2 for $10 on Amazon. They work for cables and flash drives.

I had the same Problem. Migrating from one computer to another did not work for me. I made a backup of the old computer. Then using the migration assistance I connected the backup external drive to the new computer and it ran beautifully to transfer all data to the latter in a fairly short time. I recommend you to do the same thing.