I have an account at Google. It is my account. I have not been hacked. I know the email address and password. No one else has access to the password. I have done nothing that violates any guidelines. I am able to get the verification codes when sent to my email address.
However despite all this, as of recently, whenever I try to log in, I get an error message that says,
"Verify it’s you. We noticed unusual activity in your Google Account. To keep your account safe, you were signed out. To continue, you’ll need to verify it’s you."
When I then go through the "Account Recovery" steps, enter the correct email, password and verification code, all I get is another error message that says,
"You didn’t provide enough info for Google to be sure this account is really yours."
On the the suggestions help page it says to add a recovery phone number to receive texts or to add two-step verification to the account -- but of course I can't do either of those things since I can't log into the account to make any changes to it.
If I try the "Account Recovery" process, it just sends my in an endless loop asking for email, password and verification code over and over, and always ending up at the same error messages.

I have tried logging on a normal browser page and also on an "Incognito" "private" browser page, but get the same results either way -- so Incognito doesn't help.

Twice now II have waited a full 7+ days between log in attempts, so it no longer would think there was "unusual activity," but waiting a week didn't help either time.
Why is this happening and how can I get back into my own account? I cant even request a "resolution" from Google because one must be logged in to the account to even make the request.
It is very important that I be able to log back into the account, and there's absolutely no reason why I should be frozen out.

I should add that I am attempting to log in from a "familiar device" -- the same computer I used to create the account in the first place. So there's absolutely no reason why Google thinks that it can't "verify" me -- I know the account email, I know the password, I can receive the verification emails, I correctly enter the verification codes when prompted, and I am logging in from a trusted familiar device, and I am using the same wifi network I used when I created the account. I have never been hacked, never uploaded a video, never left a comment, never received a warning, and never violated any guidelines. Nothing is unusual, nothing is suspicious, nothing has changed. And yet for no discernible reason I have been frozen out of my account -- an account that I desperately need to access. Surely there must be SOME way this can be resolved.
Help!