Google recruiters will get in touch regardless of whether you have a chance of passing the interview or there’s actually a role open that makes sense. Just went through 6+ weeks after passing their interview where they couldn’t find me a team, so took a job at another company.
Google hires a lot of people for a variety of roles. I'm sure you're very good at what you do :) but also they're a large company like any other that has a desire to recruit new talent.
I don't know if it's impostor syndrome or just sheer brand strength, but my first reaction was "why would Google be interested in me?".
Judging by the tone of those emails it might be that Google turned up the heat in HR already and people are racing to meet KPIs.