Speaking only for myself...
I often like to wear thin soft merino wool base layer tops when cycling, for various reasons: they help regulate your temperature, they don't get as smelly as polyester or lycra, they breathe and wick sweat away from you, dry quickly, and they don't feel cold and clammy if you sweat. SmartWool and Ibex brands have lots of fine soft merino for layering. Or you can get thrift store finds.

The non-wool tops I do wear are screaming neon yellow when I want to be very visible in traffic. Or I might wear a thin merino top and a screaming yellow windbreaker vest over it.
Many people like jerseys with big back pockets, especially if they have tiny bike bags. I like to keep my stuff in a roomy saddlebag on my bike instead of in pockets.
There's no law saying you have to wear a biking jersey to ride a bike.
Wear what pleases you and feels good!