Hi AllyS11,
Thanks for posting your question. Being able to log in to your Mac is critical, and I'm happy to help out as much as possible with this issue.
If you were able to boot up in safe mode while holding Shift, that does suggest at least some of the keys are responding as expected. As another test, try starting up while holding Command + R; this will bring you to macOS Utilities. Once that loads, click "Get Help Online" and then try typing in the Safari window that opens to see how that works. You can then exit by clicking Apple menu () > Restart.
As another possibility, do you have a USB keyboard available? If you do, try connecting it and then see if you're able to log in. Then disconnect the USB keyboard and try typing in a few apps in your user account.
I hope this helps get you started!
Have a good one.