Hi, I'm Robert and I'll be helping you with your computer question.
the reason that they cant do that is that if i or your worst enemy told google it is my account just send a reset link to this different email address than i would have your account
and there are thousands of people trying to do that to their friends, enemies and lovers every day.
you need to prove that it is your account. That means having access to the phone or email that was in the account BEFORE you lost control over it. or knowing an old password ***** the exact month and date that you created the account.
I can try to help you if you like. but your best bet might be trying to get his old email account opened or seeing if anybody has the old number now who will help you. or just making a new email account.