Is there ANY way to go back to the previous settings so I can turn off the two factor authentication?

No, if you've enabled two-factor authentication you can't turn if off : Two-factor authentication for Apple ID - Apple Support

If you already use two-factor authentication, you can no longer turn it off. Certain features in the latest versions of iOS and macOS require this extra level of security, which is designed to protect your information. If you recently updated your account, however, you can unenroll for a period of two weeks. Just open your enrollment confirmation email and click the link to return to your previous security settings. Keep in mind, this makes your account less secure and means that you can't use features that require a higher level of security.

See - Two-factor authentication for Apple ID - Apple Support. You may not be able to disable 2FA though. If you use some features of iOS 11.4.1 or 12 (e.g. messages in iCloud) then 2FA is required.

You can use another phone number. Or, as I do, I use one if my google voice numbers, which allows me to get messages with any web browser. That way, even without any Apple products, I can still always get access to my AppleID.

As to why why you don’t get a say - Apple is the one who holds and is responsible for the security of your personal information you choose to share with them in the form of your AppleID and the accounts you voluntarily create with Apple using that AppleID (iCloud, iMessage, FaceTime, etc accounts). Just like any other online account provider, they get to set whatever minimum security settings or features they deem necessary to secure your accounts. If you don’t like that, with Apple or any online account provider, then don’t use them.

But as the stewards of personal data, they have every right to make sure their account holders follow their choice of minimum security settings. So does every other online service provider from your banks, email providers, or whatever. And since people are notoriously lax with their own online account IDs, more and more companies are enforcing additional security features. My 401k provider recently changed their account access to require 2 factor SMS code authentication so it’s not just Apple applying greater minimum account security.

This is not solved

As far as the OP is concerned it is, they marked it as solved.

To not allowing us to control that is just absurd and unbelievable.

Obviously two-factor authentication, and you having enabled it on your account, has nothing to do with me.

How would you sing into your iCloud account and use find my phone?

If you mean sign into the account, if you read the Apple's link that I gave :

You should also consider verifying an additional phone number you can access, such as a home phone, or a number used by a family member or close friend. You can use this number if you temporarily can't access your primary number or your own devices.

and :

If you're signing in and don’t have a trusted device handy that can display verification codes, you can have a code sent to your trusted phone number via text message or an automated phone call instead. Click Didn't Get a Code on the sign in screen and choose to send a code to your trusted phone number. You can also get a code directly from Settings on a trusted device. Learn how to get a verification code.

This is not solved this is just plain stupid.

To not allowing us to control that is just absurd and unbelievable.

Please answer me what do you do in case:

You have only one iPhone and lost it. How would you sing into your iCloud account and use find my phone?

Essentially your screwed.