The talk of Mahomes as a GOAT already is just part of the typical hype that drives sports every year. No doubt he is the face of the new generation of QBs and he is off to an unprecedented start in his career when you pair his numbers with the SB wins. I personally don't believe SB wins is the best measure of individual performance but I am obviously way outnumbered.
However, by any measure, right now he isn't the GOAT or amongst the GOATs because he just hasn't played long enough to rack up the numbers to fairly decide the question. Time will tell but there is just so much hype to drive narrative in sports. It's just not sexy or tantalizing to say 'let's wait and see'. Now we are talking about Mahomes chasing Brady despite the fact that Brady played for decades, has more MVPs nearly all the big all-time stats and 6 rings. Will it surprise me if Mahomes has 6 SB rings when it's all said and done? No, because this is an amazing trajectory he appears to be on. But will it surprise me if he starts suffering injuries that impact his performance, or if at some point as he ages he can no longer scramble like he once did and doesn't do as well as a mostly pocket passer? No. We have seen that story time and time again (though, we've only seen the 6 ring story once). Football can be an unpredictable sport but sooner or later, almost everyone gets hurt.
I think his pairing with Andy Reid is special and it *could* one day look like Brady + Belicheck. We'll see in 10 years.