What's the reasoning for such ratios?
My guess is that it's because of the different kinds of muscles used - your back muscles combined are, for almost everyone, stronger / bigger than their leg muscles, which are stronger than their arm muscles. My deadlift PR was almost twice my squat PR, just as an example.
Shame. Think of it this way, then: you're beating everyone who isn't doing any weight right now. If you measure your life from the successful people's, you'll always find yourself missing something, when in fact, the truth of what you have comes from what you had and what you gained. I came to call it "measuring from zero than from a hundred", referring to percentage of achieving some sort of an ideal that we chase blindly. It's not what we don't have that defines us - it's what we do have, and right now, you have it quite well, don't you?
What I left out was that my bench PR was half my squat, and that my squat form was appaling. Either the squat weight is too light to matter or my weak as shit ankles were in the way. Everyone in the gym sucks in their own special way. That said, eat more proteins and heavy reps will get better over time. It's the trendline that counts, not the outliers.