All Google applications, the ones coming by default with the phone, keep crashing in some way or another.

It doesn't happen with any other app that I know off, even with Google apps that didn't come with the phone.

Probably related with the fact that the phone operating system hasn't seen updates since 2017-11.

I think it's because of a conflict with Android Webview. I had the same problem. 
You should try to delete the data or empty the cache for Android Webview. 
After reboot your mobile, Google play should do the updates and then you will see what will happen.