That’s precisely what makes it impressive
Yes and no.
It's always impressive to improve a win count. But not as impressive when the bar is so low. Sure, if they end up 4-8, they "improved" but are still a 4 win team. That's not a "good" team.
It's worthy of credit but taking a total trash team to a simply bad team isn't a water into wine accomplishment.
It's not easy to go from terrible to good, but the hardest thing to do is to go from good to great.
Lots of halfway competent coaches can take a terrible team and make them less bad or mediocre. A competent coach can make them good.
Deion has done a stellar job in many respects, but the real impressive job will be in years 3-4 IF he continues to win more each year.