I just can't create a composition, I had managed to make just one that out of nowhere adobe after effects started giving these errors, and I just can't create a composition (and in adobe after effects 2021)
Without any info on your computer and other details such as what settings you used when creating your composition nobody can tel lyou much. On a hunch I'd say this is a GPU crash liek so many otehrs due to using non-standard settings for a comp and now they always come back and crash, but who's to say? Could be anything. Also start by deleting the AE prefs and the GPU info log. A fresh scan and reset to defaults may fix this already.
Try to delete your After Effects preferences file. As soon as you launch AE, press and hold CONTROL+ALT+SHIFT on your keyboard and launch AE. You will be prompted to delete the preferences file. Click OK an try again.