Rethink the problem that impacts you most.
I might guess that you have some money to burn to improve your pc.
The combo of I5-6400 and GTX1060 is a good one.
Option A
As far as I know, your games are not highly threaded and can use 2-3 threads.
The ryzen upgrade to 1600 is good only of you can effectively use 5 or more threads.
The single thread processing capability is virtually identical.
I rate this option as a sideways move.
Your I5-6400 has a clock of 2.7 that is a single thread passmark rating of 1822.
If you need a cpu improvement, sell the I-6400 in favor of something like a I3-7320@4.1 passmark 2394(about $150).
Or a I3-7350K@4.2 which costs the same even if you can't overclock on your H110 motherboard.
Option B
If you now run at a steady 60fps and need more for good gaming on your games, then a faster monitor is good.
But, first see if your cpu has the power to run at higher fps.
Lower the resolution and eye candy and run your games.
If your fps improves, your cpu can handle it.
Then, you may be faced with needing a faster graphics card to match.
A plus of a good second monitor is that it makes other desktop work so much easier.
A side monitor is useful while gaming to keep such things as monitors or email open.
Option C
On keyboard and mouse, I would want to try out the specific options first before spending big bucks.
Likely, that is not convenient so buy from a place which will accept returns for a modest restocking charge.
Option D
Do you have a SSD?
It is one of the most satisfying performance upgrades you can make.