Started motorcycles in rain about 1968 in traffic. Bicycles later. Go slow, be aware of what is around you, have powerful lights, bright clothing, corner and brake lightly. You can ride across a stream.
One needs to know how to control a bike in a slide, it helps your confidence. Practice on wet grass.
Bicycles are very slow, it's relatively easy. When you corner keep the bike straight up and turn the bars. Don't brake on corners.
Salmon cool stops work on any aluminum rims even when the bottom of the wheel is submerged.
Not a big deal. I don't try and go fast in rain on the road. Mud and snow can be lots of fun sliding around. Ice too.