Cotton T shirts are often feared because they will kill you by hypothermia. Really that is overblown. It is bad to work up a sweat on a cold, damp day and then coast down a steep hill and ride for hrs in wet cotton, that may give you hypothermia. Normal commuting over 5 miles where you can regulate your temp to avoid sweat is just fine.
A lot of T shirts are made from polyester and they act as wicking materials so they dry more quickly. The expensive ones are a bit better than cheap ones but all are a lot better than cotton for getting dry.

Jeans are pretty bad cycling wear. Polyester/cotton mix hiking pants are much better: lighter, more windproof, quicker drying, thinner seams, more hardwearing. I wear mine all year round and only feel the need for long johns below -5C. I have expensive brand ones and cheap no-brand ones and they both work fine.

Get yourself a thin windproof top that is NOT waterproof. Bright colour, reflective bits
A breathable waterproof jacket.
waterproof pants
Wool socks

Wear a wicking T short (no need for a cycling jersey style)
A windproof shell.
Add midlayer insulation as required: light fleece, wool pullover.

As it gets colder, add gloves, neck-tube, more midlayer insulation. Always start off riding cool so you warm up to operating temp and avoid sweating.