I have a macbook with command line tools installed and I have homebrew installed. I think I installed Python on brew, but which git tells me I'm using /usr/bin/

I have a macbook with command line tools installed and I have homebrew installed. I think I installed Python on brew, but which git tells me I'm using /usr/bin/git for that. Is there a list somewhere of dangerously old software Apple have shipped to me that I should reinstall with brew immediately?