On my staging area I 'm developing a new form (started about 2 weeks ago and today I’ve picked this up again), however I have no control about fields, nor adding new fields.
Then I’ve tried a new, blank, form. I try to use some fields put they appear as little boxes and I can’t do anything with them
I’m unable to replicate the issue in a default WordPress installation. That suggests it is something specific to your site.
I recommend performing a conflict test. Due to the nature of the issue, the conflict test should be performed manually following the steps described here: https://docs.gravityforms.com/testing-for-a-themeplugin-conflict/
Note that for a valid conflict test, the first test must be done with only Gravity Forms enabled. All other plugins should be disabled , and a default WordPress theme without custom code should be used (e.g. Twenty Twenty-One).
If you don’t feel comfortable doing this in the live site, try creating a staging clone or sandbox setup for testing.