OP said “more people would be vegan” which I think is strictly true. Everyone? No. Would a lot of people reduce their meat consumption from the currently obscene 150+ animals per year (average American)? Probably.
I probably eat a thousand anchovies a year alone.
But anyway yes, most of the specific individuals animals killed are chickens and water creatures of various types.
Here's a pretty good analysis based on USDA data. Prediction: "Seafood don't count! for handwavehandwave reasons!"
What you are missing is the industrial process we put together in the last 70 years to produce more meat; cheaper and faster.
Those are weird, and inhuman.
Those technics make most people uncomfortable. If not, the amount of antibiotics we have to pump into the animal to keep them healthy will hirk another slice of the public.
A data point here is the % of depression in slaughter house worker. Those are the one that are exposed for real.
Not a wet meat market worker, not a fancy butcher.